diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CSharpClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CSharpClientCodegen.java
index 7d9b56b846e9..e087bfda2a25 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CSharpClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CSharpClientCodegen.java
@@ -1126,6 +1126,7 @@ public void addGenericHostSupportingFiles(final String clientPackageDir, final S
         supportingFiles.add(new SupportingFile("JsonSerializerOptionsProvider.mustache", clientPackageDir, "JsonSerializerOptionsProvider.cs"));
         supportingFiles.add(new SupportingFile("CookieContainer.mustache", clientPackageDir, "CookieContainer.cs"));
         supportingFiles.add(new SupportingFile("Option.mustache", clientPackageDir, "Option.cs"));
+        supportingFiles.add(new SupportingFile("FileParameter.mustache", clientPackageDir, "FileParameter.cs"));
 
         supportingFiles.add(new SupportingFile("IApi.mustache", sourceFolder + File.separator + packageName + File.separator + apiPackage(), getInterfacePrefix() + "Api.cs"));
 
diff --git a/modules/openapi-generator/src/main/resources/csharp/libraries/generichost/FileParameter.mustache b/modules/openapi-generator/src/main/resources/csharp/libraries/generichost/FileParameter.mustache
new file mode 100644
index 000000000000..6ebbfa231fec
--- /dev/null
+++ b/modules/openapi-generator/src/main/resources/csharp/libraries/generichost/FileParameter.mustache
@@ -0,0 +1,37 @@
+// <auto-generated>
+{{>partial_header}}
+
+{{#nrt}}
+#nullable enable
+
+{{/nrt}}
+namespace {{packageName}}.{{clientPackage}}
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    {{>visibility}} sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string{{nrt?}} FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string{{nrt?}} fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/modules/openapi-generator/src/main/resources/csharp/libraries/generichost/OperationDataType.mustache b/modules/openapi-generator/src/main/resources/csharp/libraries/generichost/OperationDataType.mustache
new file mode 100644
index 000000000000..1cd619e131f6
--- /dev/null
+++ b/modules/openapi-generator/src/main/resources/csharp/libraries/generichost/OperationDataType.mustache
@@ -0,0 +1 @@
+{{#isFile}}{{#isContainer}}List<{{packageName}}.{{clientPackage}}.FileParameter>{{>NullConditionalParameter}}{{/isContainer}}{{^isContainer}}{{packageName}}.{{clientPackage}}.FileParameter{{>NullConditionalParameter}}{{/isContainer}}{{/isFile}}{{^isFile}}{{{dataType}}}{{>NullConditionalParameter}}{{/isFile}}
\ No newline at end of file
diff --git a/modules/openapi-generator/src/main/resources/csharp/libraries/generichost/OperationSignature.mustache b/modules/openapi-generator/src/main/resources/csharp/libraries/generichost/OperationSignature.mustache
index caa9d144c52d..1d03c47e332c 100644
--- a/modules/openapi-generator/src/main/resources/csharp/libraries/generichost/OperationSignature.mustache
+++ b/modules/openapi-generator/src/main/resources/csharp/libraries/generichost/OperationSignature.mustache
@@ -1 +1 @@
-{{#lambda.joinWithComma}}{{#allParams}}{{#required}}{{{dataType}}}{{>NullConditionalParameter}}{{/required}}{{^required}}Option<{{{dataType}}}{{>NullConditionalParameter}}>{{/required}} {{paramName}}{{#notRequiredOrIsNullable}} = default{{/notRequiredOrIsNullable}}  {{/allParams}}System.Threading.CancellationToken cancellationToken = default{{^netstandard20OrLater}}(global::System.Threading.CancellationToken){{/netstandard20OrLater}}{{/lambda.joinWithComma}}
\ No newline at end of file
+{{#lambda.joinWithComma}}{{#allParams}}{{#required}}{{>OperationDataType}}{{/required}}{{^required}}Option<{{>OperationDataType}}>{{/required}} {{paramName}}{{#notRequiredOrIsNullable}} = default{{/notRequiredOrIsNullable}}  {{/allParams}}System.Threading.CancellationToken cancellationToken = default{{^netstandard20OrLater}}(global::System.Threading.CancellationToken){{/netstandard20OrLater}}{{/lambda.joinWithComma}}
\ No newline at end of file
diff --git a/modules/openapi-generator/src/main/resources/csharp/libraries/generichost/api.mustache b/modules/openapi-generator/src/main/resources/csharp/libraries/generichost/api.mustache
index f75235833fbe..b7cb22444daa 100644
--- a/modules/openapi-generator/src/main/resources/csharp/libraries/generichost/api.mustache
+++ b/modules/openapi-generator/src/main/resources/csharp/libraries/generichost/api.mustache
@@ -246,7 +246,7 @@ namespace {{packageName}}.{{apiPackage}}
 
         {{#allParams}}
         {{#-first}}
-        partial void Format{{operationId}}({{#allParams}}{{#isPrimitiveType}}ref {{/isPrimitiveType}}{{^required}}Option<{{/required}}{{{dataType}}}{{>NullConditionalParameter}}{{^required}}>{{/required}} {{paramName}}{{^-last}}, {{/-last}}{{/allParams}});
+        partial void Format{{operationId}}({{#allParams}}{{#isPrimitiveType}}ref {{/isPrimitiveType}}{{^required}}Option<{{/required}}{{>OperationDataType}}{{^required}}>{{/required}} {{paramName}}{{^-last}}, {{/-last}}{{/allParams}});
 
         {{/-first}}
         {{/allParams}}
@@ -258,7 +258,7 @@ namespace {{packageName}}.{{apiPackage}}
         /// <param name="{{paramName}}"></param>
         {{/vendorExtensions.x-not-nullable-reference-types}}
         /// <returns></returns>
-        private void Validate{{operationId}}({{#vendorExtensions.x-not-nullable-reference-types}}{{^required}}Option<{{/required}}{{{dataType}}}{{>NullConditionalParameter}}{{^required}}>{{/required}} {{paramName}}{{^-last}}, {{/-last}}{{/vendorExtensions.x-not-nullable-reference-types}})
+        private void Validate{{operationId}}({{#vendorExtensions.x-not-nullable-reference-types}}{{^required}}Option<{{/required}}{{>OperationDataType}}{{^required}}>{{/required}} {{paramName}}{{^-last}}, {{/-last}}{{/vendorExtensions.x-not-nullable-reference-types}})
         {
             {{#lambda.trimTrailingWithNewLine}}
             {{#vendorExtensions.x-not-nullable-reference-types}}
@@ -288,7 +288,7 @@ namespace {{packageName}}.{{apiPackage}}
         {{#allParams}}
         /// <param name="{{paramName}}"></param>
         {{/allParams}}
-        private void After{{operationId}}DefaultImplementation({{#lambda.joinWithComma}}{{interfacePrefix}}{{operationId}}ApiResponse apiResponseLocalVar  {{#allParams}}{{^required}}Option<{{/required}}{{{dataType}}}{{>NullConditionalParameter}}{{^required}}>{{/required}} {{paramName}}  {{/allParams}}{{/lambda.joinWithComma}})
+        private void After{{operationId}}DefaultImplementation({{#lambda.joinWithComma}}{{interfacePrefix}}{{operationId}}ApiResponse apiResponseLocalVar  {{#allParams}}{{^required}}Option<{{/required}}{{>OperationDataType}}{{^required}}>{{/required}} {{paramName}}  {{/allParams}}{{/lambda.joinWithComma}})
         {
             bool suppressDefaultLog = false;
             After{{operationId}}({{#lambda.joinWithComma}}ref suppressDefaultLog  apiResponseLocalVar  {{#allParams}}{{paramName}}  {{/allParams}}{{/lambda.joinWithComma}});
@@ -303,7 +303,7 @@ namespace {{packageName}}.{{apiPackage}}
         {{#allParams}}
         /// <param name="{{paramName}}"></param>
         {{/allParams}}
-        partial void After{{operationId}}({{#lambda.joinWithComma}}ref bool suppressDefaultLog  {{interfacePrefix}}{{operationId}}ApiResponse apiResponseLocalVar  {{#allParams}}{{^required}}Option<{{/required}}{{{dataType}}}{{>NullConditionalParameter}}{{^required}}>{{/required}} {{paramName}}  {{/allParams}}{{/lambda.joinWithComma}});
+        partial void After{{operationId}}({{#lambda.joinWithComma}}ref bool suppressDefaultLog  {{interfacePrefix}}{{operationId}}ApiResponse apiResponseLocalVar  {{#allParams}}{{^required}}Option<{{/required}}{{>OperationDataType}}{{^required}}>{{/required}} {{paramName}}  {{/allParams}}{{/lambda.joinWithComma}});
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -314,7 +314,7 @@ namespace {{packageName}}.{{apiPackage}}
         {{#allParams}}
         /// <param name="{{paramName}}"></param>
         {{/allParams}}
-        private void OnError{{operationId}}DefaultImplementation({{#lambda.joinWithComma}}Exception exceptionLocalVar  string pathFormatLocalVar  string pathLocalVar  {{#allParams}}{{^required}}Option<{{/required}}{{{dataType}}}{{>NullConditionalParameter}}{{^required}}>{{/required}} {{paramName}}  {{/allParams}}{{/lambda.joinWithComma}})
+        private void OnError{{operationId}}DefaultImplementation({{#lambda.joinWithComma}}Exception exceptionLocalVar  string pathFormatLocalVar  string pathLocalVar  {{#allParams}}{{^required}}Option<{{/required}}{{>OperationDataType}}{{^required}}>{{/required}} {{paramName}}  {{/allParams}}{{/lambda.joinWithComma}})
         {
             bool suppressDefaultLogLocalVar = false;
             OnError{{operationId}}({{#lambda.joinWithComma}}ref suppressDefaultLogLocalVar  exceptionLocalVar  pathFormatLocalVar  pathLocalVar  {{#allParams}}{{paramName}}  {{/allParams}}{{/lambda.joinWithComma}});
@@ -332,7 +332,7 @@ namespace {{packageName}}.{{apiPackage}}
         {{#allParams}}
         /// <param name="{{paramName}}"></param>
         {{/allParams}}
-        partial void OnError{{operationId}}({{#lambda.joinWithComma}}ref bool suppressDefaultLogLocalVar  Exception exceptionLocalVar  string pathFormatLocalVar  string pathLocalVar  {{#allParams}}{{^required}}Option<{{/required}}{{{dataType}}}{{>NullConditionalParameter}}{{^required}}>{{/required}} {{paramName}}  {{/allParams}}{{/lambda.joinWithComma}});
+        partial void OnError{{operationId}}({{#lambda.joinWithComma}}ref bool suppressDefaultLogLocalVar  Exception exceptionLocalVar  string pathFormatLocalVar  string pathLocalVar  {{#allParams}}{{^required}}Option<{{/required}}{{>OperationDataType}}{{^required}}>{{/required}} {{paramName}}  {{/allParams}}{{/lambda.joinWithComma}});
 
         /// <summary>
         /// {{summary}} {{notes}}
@@ -471,35 +471,90 @@ namespace {{packageName}}.{{apiPackage}}
                     {{/headerParams}}
                     {{#formParams}}
                     {{#-first}}
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    {{#isMultipart}}
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
-                    List<KeyValuePair<string{{nrt?}}, string{{nrt?}}>> formParameterLocalVars = new List<KeyValuePair<string{{nrt?}}, string{{nrt?}}>>();
+                    {{/isMultipart}}
+                    List<KeyValuePair<string, string{{nrt?}}>> formParameterLocalVars = new List<KeyValuePair<string, string{{nrt?}}>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));{{/-first}}{{^isFile}}{{#required}}
-
-                    formParameterLocalVars.Add(new KeyValuePair<string{{nrt?}}, string{{nrt?}}>("{{baseName}}", ClientUtils.ParameterToString({{paramName}})));
+                    {{/-first}}
+                    {{^isFile}}
+                    {{#required}}
+                    formParameterLocalVars.Add(new KeyValuePair<string, string{{nrt?}}>("{{baseName}}", ClientUtils.ParameterToString({{paramName}})));
 
                     {{/required}}
                     {{^required}}
                     if ({{paramName}}.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string{{nrt?}}, string{{nrt?}}>("{{baseName}}", ClientUtils.ParameterToString({{paramName}}.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string{{nrt?}}>("{{baseName}}", ClientUtils.ParameterToString({{paramName}}.Value)));
 
                     {{/required}}
                     {{/isFile}}
                     {{#isFile}}
+                    {{^isMultipart}}
+                    {{! application/x-www-form-urlencoded encodes everything as text key=value pairs and has no mechanism to carry binary data. File params require multipart/form-data.}}
                     {{#required}}
-                    multipartContentLocalVar.Add(new StreamContent({{paramName}}));
+                    throw new NotSupportedException("File parameters cannot be sent with application/x-www-form-urlencoded. Change the operation's content type to multipart/form-data.");
 
                     {{/required}}
                     {{^required}}
                     if ({{paramName}}.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent({{paramName}}.Value));
+                        throw new NotSupportedException("File parameters cannot be sent with application/x-www-form-urlencoded. Change the operation's content type to multipart/form-data.");
 
                     {{/required}}
+                    {{/isMultipart}}
+                    {{#isMultipart}}
+                    {{#required}}
+                    {{#isContainer}}
+                    foreach ({{packageName}}.{{clientPackage}}.FileParameter fileParameterLocalVar in {{paramName}})
+                    {
+                        var streamContentLocalVar = new StreamContent(fileParameterLocalVar.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "{{baseName}}", fileParameterLocalVar.FileName ?? "{{baseName}}");
+                    }
+
+                    {{/isContainer}}
+                    {{^isContainer}}
+                    {
+                        var streamContentLocalVar = new StreamContent({{paramName}}.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "{{baseName}}", {{paramName}}.FileName ?? "{{baseName}}");
+                    }
+
+                    {{/isContainer}}
+                    {{/required}}
+                    {{^required}}
+                    if ({{paramName}}.IsSet)
+                    {
+                        {{#isContainer}}
+                        foreach ({{packageName}}.{{clientPackage}}.FileParameter fileParameterLocalVar in {{paramName}}.Value)
+                        {
+                            var streamContentLocalVar = new StreamContent(fileParameterLocalVar.Content);
+                            multipartContentLocalVar.Add(streamContentLocalVar, "{{baseName}}", fileParameterLocalVar.FileName ?? "{{baseName}}");
+                        }
+                        {{/isContainer}}
+                        {{^isContainer}}
+                        var streamContentLocalVar = new StreamContent({{paramName}}.Value.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "{{baseName}}", {{paramName}}.Value.FileName ?? "{{baseName}}");
+                        {{/isContainer}}
+                    }
+
+                    {{/required}}
+                    {{/isMultipart}}
                     {{/isFile}}
                     {{/formParams}}
+                    {{#formParams}}
+                    {{#-first}}
+                    {{#isMultipart}}
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
+                    {{/isMultipart}}
+                    {{^isMultipart}}
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+                    {{/isMultipart}}
+
+                    {{/-first}}
+                    {{/formParams}}
                     {{#bodyParam}}
                     {{#required}}
                     httpRequestMessageLocalVar.Content = ({{paramName}}{{^required}}.Value{{/required}} as object) is System.IO.Stream stream
@@ -587,10 +642,12 @@ namespace {{packageName}}.{{apiPackage}}
                     {{#consumes}}
                     {{#-first}}
 
+                    {{^formParams}}
                     string{{nrt?}} contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
 
                     if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
                         httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
+                    {{/formParams}}
 
                     {{/-first}}
                     {{/consumes}}
diff --git a/modules/openapi-generator/src/main/resources/csharp/libraries/generichost/api_test.mustache b/modules/openapi-generator/src/main/resources/csharp/libraries/generichost/api_test.mustache
index 32eb2b769f31..7e0b704c1a01 100644
--- a/modules/openapi-generator/src/main/resources/csharp/libraries/generichost/api_test.mustache
+++ b/modules/openapi-generator/src/main/resources/csharp/libraries/generichost/api_test.mustache
@@ -35,7 +35,7 @@ namespace {{packageName}}.Test.{{apiPackage}}
         public async Task {{operationId}}AsyncTest()
         {
             {{#allParams}}
-            {{^required}}Client.Option<{{/required}}{{{dataType}}}{{>NullConditionalParameter}}{{^required}}>{{/required}} {{paramName}} = default{{nrt!}};
+            {{^required}}Client.Option<{{/required}}{{>OperationDataType}}{{^required}}>{{/required}} {{paramName}} = default{{nrt!}};
             {{/allParams}}
             {{#responses}}
             {{#-first}}
diff --git a/modules/openapi-generator/src/test/resources/3_0/csharp/petstore-with-fake-endpoints-models-for-testing-with-http-signature.yaml b/modules/openapi-generator/src/test/resources/3_0/csharp/petstore-with-fake-endpoints-models-for-testing-with-http-signature.yaml
index 1c9e901ad0dd..2edf96c9c3c3 100644
--- a/modules/openapi-generator/src/test/resources/3_0/csharp/petstore-with-fake-endpoints-models-for-testing-with-http-signature.yaml
+++ b/modules/openapi-generator/src/test/resources/3_0/csharp/petstore-with-fake-endpoints-models-for-testing-with-http-signature.yaml
@@ -316,6 +316,46 @@ paths:
                   description: file to upload
                   type: string
                   format: binary
+  '/pet/{petId}/uploadImages':
+    post:
+      tags:
+        - pet
+      summary: uploads an images
+      description: ''
+      operationId: uploadFiles
+      parameters:
+        - name: petId
+          in: path
+          description: ID of pet to update
+          required: true
+          schema:
+            type: integer
+            format: int64
+      responses:
+        '200':
+          description: successful operation
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ApiResponse'
+      security:
+        - petstore_auth:
+            - 'write:pets'
+            - 'read:pets'
+      requestBody:
+        required: true
+        content:
+          multipart/form-data:
+            schema:
+              type: object
+              properties:
+                files:
+                  type: array
+                  items:
+                    type: string
+                    format: binary
+              required:
+                - files
   /store/inventory:
     get:
       tags:
diff --git a/samples/client/petstore/csharp/generichost/latest/ComposedEnum/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/latest/ComposedEnum/.openapi-generator/FILES
index a0b893ad3a65..088165b19c1d 100644
--- a/samples/client/petstore/csharp/generichost/latest/ComposedEnum/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/latest/ComposedEnum/.openapi-generator/FILES
@@ -23,6 +23,7 @@ src/Org.OpenAPITools/Client/DateOnlyNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/JsonSerializerOptionsProvider.cs
 src/Org.OpenAPITools/Client/Option.cs
diff --git a/samples/client/petstore/csharp/generichost/latest/ComposedEnum/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/latest/ComposedEnum/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..42e3a7879497
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/latest/ComposedEnum/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,42 @@
+// <auto-generated>
+/*
+ * OpenAPI
+ *
+ * OpenAPI
+ *
+ * The version of the OpenAPI document: 0.0.1
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+#nullable enable
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string? FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string? fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/latest/HelloWorld/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/latest/HelloWorld/.openapi-generator/FILES
index 479e2c02cc5c..7e49740eadbb 100644
--- a/samples/client/petstore/csharp/generichost/latest/HelloWorld/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/latest/HelloWorld/.openapi-generator/FILES
@@ -23,6 +23,7 @@ src/Org.OpenAPITools/Client/DateOnlyNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/JsonSerializerOptionsProvider.cs
 src/Org.OpenAPITools/Client/Option.cs
diff --git a/samples/client/petstore/csharp/generichost/latest/HelloWorld/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/latest/HelloWorld/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..edb0bd0479a5
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/latest/HelloWorld/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,42 @@
+// <auto-generated>
+/*
+ * Minimal reproduction for csharp webhook bug
+ *
+ * This is an example API to reproduce a bug with webhooks in csharp codegen
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+#nullable enable
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string? FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string? fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/latest/InlineEnumAnyOf/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/latest/InlineEnumAnyOf/.openapi-generator/FILES
index 8f168c503eca..7c3137c1b51f 100644
--- a/samples/client/petstore/csharp/generichost/latest/InlineEnumAnyOf/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/latest/InlineEnumAnyOf/.openapi-generator/FILES
@@ -26,6 +26,7 @@ src/Org.OpenAPITools/Client/DateOnlyNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/JsonSerializerOptionsProvider.cs
 src/Org.OpenAPITools/Client/Option.cs
diff --git a/samples/client/petstore/csharp/generichost/latest/InlineEnumAnyOf/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/latest/InlineEnumAnyOf/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..77779fe7d75a
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/latest/InlineEnumAnyOf/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,42 @@
+// <auto-generated>
+/*
+ * OpenAPI Petstore
+ *
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+#nullable enable
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string? FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string? fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/latest/OneOfList/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/latest/OneOfList/.openapi-generator/FILES
index c3094ea1e371..54155a05db81 100644
--- a/samples/client/petstore/csharp/generichost/latest/OneOfList/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/latest/OneOfList/.openapi-generator/FILES
@@ -24,6 +24,7 @@ src/Org.OpenAPITools/Client/DateOnlyNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/JsonSerializerOptionsProvider.cs
 src/Org.OpenAPITools/Client/Option.cs
diff --git a/samples/client/petstore/csharp/generichost/latest/OneOfList/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/latest/OneOfList/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..f5b898e16331
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/latest/OneOfList/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,42 @@
+// <auto-generated>
+/*
+ * Oneof array test
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+#nullable enable
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string? FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string? fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/latest/Tags/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/latest/Tags/.openapi-generator/FILES
index b08037a54926..27397861417c 100644
--- a/samples/client/petstore/csharp/generichost/latest/Tags/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/latest/Tags/.openapi-generator/FILES
@@ -27,6 +27,7 @@ src/Org.OpenAPITools/Client/DateOnlyNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/JsonSerializerOptionsProvider.cs
 src/Org.OpenAPITools/Client/Option.cs
diff --git a/samples/client/petstore/csharp/generichost/latest/Tags/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/latest/Tags/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..1e3e3f9f418f
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/latest/Tags/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,43 @@
+// <auto-generated>
+/*
+ * Files.com API
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * The version of the OpenAPI document: 0.0.1
+ * Contact: support@files.com
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+#nullable enable
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string? FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string? fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net10/AllOf/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net10/AllOf/.openapi-generator/FILES
index b9ab612bd8b5..46a8286dea29 100644
--- a/samples/client/petstore/csharp/generichost/net10/AllOf/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net10/AllOf/.openapi-generator/FILES
@@ -25,6 +25,7 @@ src/Org.OpenAPITools/Client/DateOnlyNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/JsonSerializerOptionsProvider.cs
 src/Org.OpenAPITools/Client/Option.cs
diff --git a/samples/client/petstore/csharp/generichost/net10/AllOf/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net10/AllOf/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..1913a3a0f2d9
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net10/AllOf/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,42 @@
+// <auto-generated>
+/*
+ * Example
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+#nullable enable
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string? FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string? fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net10/AnyOf/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net10/AnyOf/.openapi-generator/FILES
index dc42a5d47091..072cc8408121 100644
--- a/samples/client/petstore/csharp/generichost/net10/AnyOf/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net10/AnyOf/.openapi-generator/FILES
@@ -25,6 +25,7 @@ src/Org.OpenAPITools/Client/DateOnlyNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/JsonSerializerOptionsProvider.cs
 src/Org.OpenAPITools/Client/Option.cs
diff --git a/samples/client/petstore/csharp/generichost/net10/AnyOf/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net10/AnyOf/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..e629f4afdaec
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net10/AnyOf/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,42 @@
+// <auto-generated>
+/*
+ * fruity
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * The version of the OpenAPI document: 0.0.1
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+#nullable enable
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string? FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string? fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net10/AnyOfNoCompare/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net10/AnyOfNoCompare/.openapi-generator/FILES
index dc42a5d47091..072cc8408121 100644
--- a/samples/client/petstore/csharp/generichost/net10/AnyOfNoCompare/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net10/AnyOfNoCompare/.openapi-generator/FILES
@@ -25,6 +25,7 @@ src/Org.OpenAPITools/Client/DateOnlyNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/JsonSerializerOptionsProvider.cs
 src/Org.OpenAPITools/Client/Option.cs
diff --git a/samples/client/petstore/csharp/generichost/net10/AnyOfNoCompare/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net10/AnyOfNoCompare/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..e629f4afdaec
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net10/AnyOfNoCompare/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,42 @@
+// <auto-generated>
+/*
+ * fruity
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * The version of the OpenAPI document: 0.0.1
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+#nullable enable
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string? FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string? fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net10/FormModels/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net10/FormModels/.openapi-generator/FILES
index a9823b3075fd..737d53400248 100644
--- a/samples/client/petstore/csharp/generichost/net10/FormModels/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net10/FormModels/.openapi-generator/FILES
@@ -165,6 +165,7 @@ src/Org.OpenAPITools/Client/DateOnlyNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningToken.cs
diff --git a/samples/client/petstore/csharp/generichost/net10/FormModels/api/openapi.yaml b/samples/client/petstore/csharp/generichost/net10/FormModels/api/openapi.yaml
index a9ab8dd51c13..7017affc0b9c 100644
--- a/samples/client/petstore/csharp/generichost/net10/FormModels/api/openapi.yaml
+++ b/samples/client/petstore/csharp/generichost/net10/FormModels/api/openapi.yaml
@@ -326,6 +326,40 @@ paths:
       summary: uploads an image
       tags:
       - pet
+  /pet/{petId}/uploadImages:
+    post:
+      description: ""
+      operationId: uploadFiles
+      parameters:
+      - description: ID of pet to update
+        explode: false
+        in: path
+        name: petId
+        required: true
+        schema:
+          format: int64
+          type: integer
+        style: simple
+      requestBody:
+        content:
+          multipart/form-data:
+            schema:
+              $ref: "#/components/schemas/uploadFiles_request"
+        required: true
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ApiResponse"
+          description: successful operation
+      security:
+      - petstore_auth:
+        - write:pets
+        - read:pets
+      summary: uploads an images
+      tags:
+      - pet
   /store/inventory:
     get:
       description: Returns a map of status codes to quantities
@@ -2748,6 +2782,16 @@ components:
           format: binary
           type: string
       type: object
+    uploadFiles_request:
+      properties:
+        files:
+          items:
+            format: binary
+            type: string
+          type: array
+      required:
+      - files
+      type: object
     testEnumParameters_request_enum_form_string_array_inner:
       default: $
       enum:
diff --git a/samples/client/petstore/csharp/generichost/net10/FormModels/docs/apis/PetApi.md b/samples/client/petstore/csharp/generichost/net10/FormModels/docs/apis/PetApi.md
index e32c1e31e089..59d4ef8e6df0 100644
--- a/samples/client/petstore/csharp/generichost/net10/FormModels/docs/apis/PetApi.md
+++ b/samples/client/petstore/csharp/generichost/net10/FormModels/docs/apis/PetApi.md
@@ -13,6 +13,7 @@ All URIs are relative to *http://petstore.swagger.io:80/v2*
 | [**UpdatePetWithForm**](PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data |
 | [**UploadFile**](PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image |
 | [**UploadFileWithRequiredFile**](PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required) |
+| [**UploadFiles**](PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images |
 
 <a id="addpet"></a>
 # **AddPet**
@@ -341,3 +342,38 @@ uploads an image (required)
 
 [[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
 
+<a id="uploadfiles"></a>
+# **UploadFiles**
+> ApiResponse UploadFiles (List<System.IO.Stream> files, long petId)
+
+uploads an images
+
+
+### Parameters
+
+| Name | Type | Description | Notes |
+|------|------|-------------|-------|
+| **files** | **List&lt;System.IO.Stream&gt;** |  |  |
+| **petId** | **long** | ID of pet to update |  |
+
+### Return type
+
+[**ApiResponse**](ApiResponse.md)
+
+### Authorization
+
+[petstore_auth](../README.md#petstore_auth)
+
+### HTTP request headers
+
+ - **Content-Type**: multipart/form-data
+ - **Accept**: application/json
+
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **200** | successful operation |  -  |
+
+[[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
+
diff --git a/samples/client/petstore/csharp/generichost/net10/FormModels/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs b/samples/client/petstore/csharp/generichost/net10/FormModels/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
index 495d785314c5..1924842cdbef 100644
--- a/samples/client/petstore/csharp/generichost/net10/FormModels/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/net10/FormModels/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
@@ -196,7 +196,7 @@ public async Task TestEndpointParametersAsyncTest()
             string patternWithoutDelimiter = default;
             byte[] varByte = default;
             double varDouble = default;
-            Client.Option<System.IO.Stream> binary = default;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> binary = default;
             Client.Option<string> callback = default;
             Client.Option<DateOnly> date = default;
             Client.Option<DateTime> dateTime = default;
diff --git a/samples/client/petstore/csharp/generichost/net10/FormModels/src/Org.OpenAPITools.Test/Api/PetApiTests.cs b/samples/client/petstore/csharp/generichost/net10/FormModels/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
index 1f1d7f6c4576..a4aa8f3e245d 100644
--- a/samples/client/petstore/csharp/generichost/net10/FormModels/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/net10/FormModels/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
@@ -137,7 +137,7 @@ public async Task UploadFileAsyncTest()
         {
             long petId = default;
             Client.Option<string> additionalMetadata = default;
-            Client.Option<System.IO.Stream> file = default;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> file = default;
             var response = await _instance.UploadFileAsync(petId, additionalMetadata, file);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
@@ -150,11 +150,24 @@ public async Task UploadFileAsyncTest()
         public async Task UploadFileWithRequiredFileAsyncTest()
         {
             long petId = default;
-            System.IO.Stream requiredFile = default;
+            Org.OpenAPITools.Client.FileParameter requiredFile = default;
             Client.Option<string> additionalMetadata = default;
             var response = await _instance.UploadFileWithRequiredFileAsync(petId, requiredFile, additionalMetadata);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
         }
+
+        /// <summary>
+        /// Test UploadFiles
+        /// </summary>
+        [Fact (Skip = "not implemented")]
+        public async Task UploadFilesAsyncTest()
+        {
+            List<Org.OpenAPITools.Client.FileParameter> files = default;
+            long petId = default;
+            var response = await _instance.UploadFilesAsync(files, petId);
+            var model = response.Ok();
+            Assert.IsType<ApiResponse>(model);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/net10/FormModels/src/Org.OpenAPITools/Api/DefaultApi.cs b/samples/client/petstore/csharp/generichost/net10/FormModels/src/Org.OpenAPITools/Api/DefaultApi.cs
index 3c26a27185e6..44d52e7e1090 100644
--- a/samples/client/petstore/csharp/generichost/net10/FormModels/src/Org.OpenAPITools/Api/DefaultApi.cs
+++ b/samples/client/petstore/csharp/generichost/net10/FormModels/src/Org.OpenAPITools/Api/DefaultApi.cs
@@ -764,27 +764,19 @@ public async Task<IGetCountryApiResponse> GetCountryAsync(string country, System
                         ? "/country"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/country");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("country", ClientUtils.ParameterToString(country)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/net10/FormModels/src/Org.OpenAPITools/Api/FakeApi.cs b/samples/client/petstore/csharp/generichost/net10/FormModels/src/Org.OpenAPITools/Api/FakeApi.cs
index 2a332dbf1eb9..0070617289e6 100644
--- a/samples/client/petstore/csharp/generichost/net10/FormModels/src/Org.OpenAPITools/Api/FakeApi.cs
+++ b/samples/client/petstore/csharp/generichost/net10/FormModels/src/Org.OpenAPITools/Api/FakeApi.cs
@@ -330,7 +330,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -354,7 +354,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// To test enum parameters
@@ -4080,7 +4080,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<System.IO.Stream> binary, ref Option<string> callback, ref Option<DateOnly> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
+        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<Org.OpenAPITools.Client.FileParameter> binary, ref Option<string> callback, ref Option<DateOnly> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
 
         /// <summary>
         /// Validates the request parameters
@@ -4092,7 +4092,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="password"></param>
         /// <param name="varString"></param>
         /// <returns></returns>
-        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<System.IO.Stream> binary, Option<string> callback, Option<string> password, Option<string> varString)
+        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<string> password, Option<string> varString)
         {
             if (patternWithoutDelimiter == null)
                 throw new ArgumentNullException(nameof(patternWithoutDelimiter));
@@ -4131,7 +4131,7 @@ private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLog = false;
             AfterTestEndpointParameters(ref suppressDefaultLog, apiResponseLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4158,7 +4158,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -4180,7 +4180,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorTestEndpointParameters(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4209,7 +4209,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트  Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -4230,7 +4230,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -4262,7 +4262,7 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDe
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -4281,14 +4281,8 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         ? "/fake"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("number", ClientUtils.ParameterToString(number)));
 
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("pattern_without_delimiter", ClientUtils.ParameterToString(patternWithoutDelimiter)));
@@ -4298,7 +4292,7 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("double", ClientUtils.ParameterToString(varDouble)));
 
                     if (binary.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(binary.Value));
+                        throw new NotSupportedException("File parameters cannot be sent with application/x-www-form-urlencoded. Change the operation's content type to multipart/form-data.");
 
                     if (callback.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("callback", ClientUtils.ParameterToString(callback.Value)));
@@ -4327,6 +4321,9 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                     if (varString.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("string", ClientUtils.ParameterToString(varString.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -4340,11 +4337,6 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -4625,29 +4617,23 @@ public async Task<ITestEnumParametersApiResponse> TestEnumParametersAsync(Option
                     if (enumHeaderStringArray.IsSet)
                         httpRequestMessageLocalVar.Headers.Add("enum_header_string_array", ClientUtils.ParameterToString(enumHeaderStringArray.Value));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (enumFormString.IsSet)
+                    if (enumFormString.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("enum_form_string", ClientUtils.ParameterToString(enumFormString.Value)));
 
                     if (enumFormStringArray.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("enum_form_string_array", ClientUtils.ParameterToString(enumFormStringArray.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Get;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -5534,29 +5520,21 @@ public async Task<ITestJsonFormDataApiResponse> TestJsonFormDataAsync(string par
                         ? "/fake/jsonFormData"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/jsonFormData");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("param", ClientUtils.ParameterToString(param)));
 
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("param2", ClientUtils.ParameterToString(param2)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Get;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/net10/FormModels/src/Org.OpenAPITools/Api/PetApi.cs b/samples/client/petstore/csharp/generichost/net10/FormModels/src/Org.OpenAPITools/Api/PetApi.cs
index d07d16c30828..fd403446d9a6 100644
--- a/samples/client/petstore/csharp/generichost/net10/FormModels/src/Org.OpenAPITools/Api/PetApi.cs
+++ b/samples/client/petstore/csharp/generichost/net10/FormModels/src/Org.OpenAPITools/Api/PetApi.cs
@@ -216,7 +216,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image
@@ -229,7 +229,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -243,7 +243,7 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -256,7 +256,32 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        Task<IUploadFilesApiResponse> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
     }
 
     /// <summary>
@@ -415,6 +440,18 @@ public interface IUploadFileWithRequiredFileApiResponse : Org.OpenAPITools.Clien
         bool IsOk { get; }
     }
 
+    /// <summary>
+    /// The <see cref="IUploadFilesApiResponse"/>
+    /// </summary>
+    public interface IUploadFilesApiResponse : Org.OpenAPITools.Client.IApiResponse, IOk<Org.OpenAPITools.Model.ApiResponse>
+    {
+        /// <summary>
+        /// Returns true if the response is 200 Ok
+        /// </summary>
+        /// <returns></returns>
+        bool IsOk { get; }
+    }
+
     /// <summary>
     /// Represents a collection of functions to interact with the API endpoints
     /// </summary>
@@ -599,6 +636,26 @@ internal void ExecuteOnErrorUploadFileWithRequiredFile(Exception exception)
         {
             OnErrorUploadFileWithRequiredFile?.Invoke(this, new ExceptionEventArgs(exception));
         }
+
+        /// <summary>
+        /// The event raised after the server response
+        /// </summary>
+        public event EventHandler<ApiResponseEventArgs> OnUploadFiles;
+
+        /// <summary>
+        /// The event raised after an error querying the server
+        /// </summary>
+        public event EventHandler<ExceptionEventArgs> OnErrorUploadFiles;
+
+        internal void ExecuteOnUploadFiles(PetApi.UploadFilesApiResponse apiResponse)
+        {
+            OnUploadFiles?.Invoke(this, new ApiResponseEventArgs(apiResponse));
+        }
+
+        internal void ExecuteOnErrorUploadFiles(Exception exception)
+        {
+            OnErrorUploadFiles?.Invoke(this, new ExceptionEventArgs(exception));
+        }
     }
 
     /// <summary>
@@ -2330,18 +2387,17 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (name.IsSet)
+                    if (name.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("name", ClientUtils.ParameterToString(name.Value)));
 
                     if (status.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("status", ClientUtils.ParameterToString(status.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -2355,11 +2411,6 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -2459,7 +2510,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<System.IO.Stream> file);
+        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Validates the request parameters
@@ -2467,7 +2518,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
         /// <returns></returns>
-        private void ValidateUploadFile(Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void ValidateUploadFile(Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             if (additionalMetadata.IsSet && additionalMetadata.Value == null)
                 throw new ArgumentNullException(nameof(additionalMetadata));
@@ -2483,7 +2534,7 @@ private void ValidateUploadFile(Option<string> additionalMetadata, Option<System
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLog = false;
             AfterUploadFile(ref suppressDefaultLog, apiResponseLocalVar, petId, additionalMetadata, file);
@@ -2499,7 +2550,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2510,7 +2561,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, additionalMetadata, file);
@@ -2528,7 +2579,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// uploads an image 
@@ -2538,7 +2589,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2559,7 +2610,7 @@ public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, O
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2579,17 +2630,23 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImage");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (additionalMetadata.IsSet)
+                    if (additionalMetadata.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
 
                     if (file.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(file.Value));
+                    {
+                        var streamContentLocalVar = new StreamContent(file.Value.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "file", file.Value.FileName ?? "file");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -2604,11 +2661,6 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         "multipart/form-data"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json"
                     };
@@ -2749,7 +2801,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFileWithRequiredFile(ref long petId, ref System.IO.Stream requiredFile, ref Option<string> additionalMetadata);
+        partial void FormatUploadFileWithRequiredFile(ref long petId, ref Org.OpenAPITools.Client.FileParameter requiredFile, ref Option<string> additionalMetadata);
 
         /// <summary>
         /// Validates the request parameters
@@ -2757,7 +2809,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
         /// <returns></returns>
-        private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void ValidateUploadFileWithRequiredFile(Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             if (requiredFile == null)
                 throw new ArgumentNullException(nameof(requiredFile));
@@ -2773,7 +2825,7 @@ private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, O
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLog = false;
             AfterUploadFileWithRequiredFile(ref suppressDefaultLog, apiResponseLocalVar, petId, requiredFile, additionalMetadata);
@@ -2789,7 +2841,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2800,7 +2852,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFileWithRequiredFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, requiredFile, additionalMetadata);
@@ -2818,7 +2870,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// uploads an image (required) 
@@ -2828,7 +2880,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2849,7 +2901,7 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2869,17 +2921,23 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/{petId}/uploadImageWithRequiredFile");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    multipartContentLocalVar.Add(new StreamContent(requiredFile));
+                    {
+                        var streamContentLocalVar = new StreamContent(requiredFile.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "requiredFile", requiredFile.FileName ?? "requiredFile");
+                    }
 
                     if (additionalMetadata.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
 
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -2893,11 +2951,6 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         "multipart/form-data"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json",
                         "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
@@ -3038,5 +3091,283 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
 
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
+
+        partial void FormatUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files, ref long petId);
+
+        /// <summary>
+        /// Validates the request parameters
+        /// </summary>
+        /// <param name="files"></param>
+        /// <returns></returns>
+        private void ValidateUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files)
+        {
+            if (files == null)
+                throw new ArgumentNullException(nameof(files));
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void AfterUploadFilesDefaultImplementation(IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLog = false;
+            AfterUploadFiles(ref suppressDefaultLog, apiResponseLocalVar, files, petId);
+            if (!suppressDefaultLog)
+                Logger.LogInformation("{0,-9} | {1} | {2}", (apiResponseLocalVar.DownloadedAt - apiResponseLocalVar.RequestedAt).TotalSeconds, apiResponseLocalVar.StatusCode, apiResponseLocalVar.Path);
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="suppressDefaultLog"></param>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void AfterUploadFiles(ref bool suppressDefaultLog, IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// Logs exceptions that occur while retrieving the server response
+        /// </summary>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void OnErrorUploadFilesDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLogLocalVar = false;
+            OnErrorUploadFiles(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, files, petId);
+            if (!suppressDefaultLogLocalVar)
+                Logger.LogError(exceptionLocalVar, "An error occurred while sending the request to the server.");
+        }
+
+        /// <summary>
+        /// A partial method that gives developers a way to provide customized exception handling
+        /// </summary>
+        /// <param name="suppressDefaultLogLocalVar"></param>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void OnErrorUploadFiles(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            try
+            {
+                return await UploadFilesAsync(files, petId, cancellationToken).ConfigureAwait(false);
+            }
+            catch (Exception)
+            {
+                return null;
+            }
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            UriBuilder uriBuilderLocalVar = new UriBuilder();
+
+            try
+            {
+                ValidateUploadFiles(files);
+
+                FormatUploadFiles(files, ref petId);
+
+                using (HttpRequestMessage httpRequestMessageLocalVar = new HttpRequestMessage())
+                {
+                    uriBuilderLocalVar.Host = HttpClient.BaseAddress.Host;
+                    uriBuilderLocalVar.Port = HttpClient.BaseAddress.Port;
+                    uriBuilderLocalVar.Scheme = HttpClient.BaseAddress.Scheme;
+                    uriBuilderLocalVar.Path = HttpClient.BaseAddress.AbsolutePath == "/"
+                        ? "/pet/{petId}/uploadImages"
+                        : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImages");
+                    uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
+
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
+
+                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+
+                    List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
+
+                    foreach (Org.OpenAPITools.Client.FileParameter fileParameterLocalVar in files)
+                    {
+                        var streamContentLocalVar = new StreamContent(fileParameterLocalVar.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "files", fileParameterLocalVar.FileName ?? "files");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
+
+                    List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
+                    httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
+
+                    OAuthToken oauthTokenLocalVar1 = (OAuthToken) await OauthTokenProvider.GetAsync(cancellation: cancellationToken).ConfigureAwait(false);
+
+                    tokenBaseLocalVars.Add(oauthTokenLocalVar1);
+
+                    oauthTokenLocalVar1.UseInHeader(httpRequestMessageLocalVar, "");
+
+                    string[] contentTypes = new string[] {
+                        "multipart/form-data"
+                    };
+
+                    string[] acceptLocalVars = new string[] {
+                        "application/json"
+                    };
+
+                    IEnumerable<MediaTypeWithQualityHeaderValue> acceptHeaderValuesLocalVar = ClientUtils.SelectHeaderAcceptArray(acceptLocalVars);
+
+                    foreach (var acceptLocalVar in acceptHeaderValuesLocalVar)
+                        httpRequestMessageLocalVar.Headers.Accept.Add(acceptLocalVar);
+
+                    httpRequestMessageLocalVar.Method = HttpMethod.Post;
+
+                    DateTime requestedAtLocalVar = DateTime.UtcNow;
+
+                    using (HttpResponseMessage httpResponseMessageLocalVar = await HttpClient.SendAsync(httpRequestMessageLocalVar, cancellationToken).ConfigureAwait(false))
+                    {
+                        ILogger<UploadFilesApiResponse> apiResponseLoggerLocalVar = LoggerFactory.CreateLogger<UploadFilesApiResponse>();
+                        UploadFilesApiResponse apiResponseLocalVar;
+
+                        switch ((int)httpResponseMessageLocalVar.StatusCode) {
+                            default: {
+                                string responseContentLocalVar = await httpResponseMessageLocalVar.Content.ReadAsStringAsync(cancellationToken).ConfigureAwait(false);
+                                apiResponseLocalVar = new(apiResponseLoggerLocalVar, httpRequestMessageLocalVar, httpResponseMessageLocalVar, responseContentLocalVar, "/pet/{petId}/uploadImages", requestedAtLocalVar, _jsonSerializerOptions);
+
+                                break;
+                            }
+                        }
+
+                        AfterUploadFilesDefaultImplementation(apiResponseLocalVar, files, petId);
+
+                        Events.ExecuteOnUploadFiles(apiResponseLocalVar);
+
+                        if (apiResponseLocalVar.StatusCode == (HttpStatusCode) 429)
+                            foreach(TokenBase tokenBaseLocalVar in tokenBaseLocalVars)
+                                tokenBaseLocalVar.BeginRateLimit();
+
+                        return apiResponseLocalVar;
+                    }
+                }
+            }
+            catch(Exception e)
+            {
+                OnErrorUploadFilesDefaultImplementation(e, "/pet/{petId}/uploadImages", uriBuilderLocalVar.Path, files, petId);
+                Events.ExecuteOnErrorUploadFiles(e);
+                throw;
+            }
+        }
+
+        /// <summary>
+        /// The <see cref="UploadFilesApiResponse"/>
+        /// </summary>
+        public partial class UploadFilesApiResponse : Org.OpenAPITools.Client.ApiResponse, IUploadFilesApiResponse
+        {
+            /// <summary>
+            /// The logger
+            /// </summary>
+            public ILogger<UploadFilesApiResponse> Logger { get; }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="rawContent"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, string rawContent, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, rawContent, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="contentStream"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, System.IO.Stream contentStream, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, contentStream, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            partial void OnCreated(global::System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage);
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public bool IsOk => 200 == (int)StatusCode;
+
+            /// <summary>
+            /// Deserializes the response if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public Org.OpenAPITools.Model.ApiResponse Ok()
+            {
+                // This logic may be modified with the AsModel.mustache template
+                return IsOk
+                    ? System.Text.Json.JsonSerializer.Deserialize<Org.OpenAPITools.Model.ApiResponse>(RawContent, _jsonSerializerOptions)
+                    : null;
+            }
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok and the deserialized response is not null
+            /// </summary>
+            /// <param name="result"></param>
+            /// <returns></returns>
+            public bool TryOk([NotNullWhen(true)]out Org.OpenAPITools.Model.ApiResponse result)
+            {
+                result = null;
+
+                try
+                {
+                    result = Ok();
+                } catch (Exception e)
+                {
+                    OnDeserializationErrorDefaultImplementation(e, (HttpStatusCode)200);
+                }
+
+                return result != null;
+            }
+
+            private void OnDeserializationErrorDefaultImplementation(Exception exception, HttpStatusCode httpStatusCode)
+            {
+                bool suppressDefaultLog = false;
+                OnDeserializationError(ref suppressDefaultLog, exception, httpStatusCode);
+                if (!suppressDefaultLog)
+                    Logger.LogError(exception, "An error occurred while deserializing the {code} response.", httpStatusCode);
+            }
+
+            partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/net10/FormModels/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net10/FormModels/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..6150dbcf4774
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net10/FormModels/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,40 @@
+// <auto-generated>
+/*
+ * OpenAPI Petstore
+ *
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/.openapi-generator/FILES
index ab28c754b4b1..a3e02b328e0a 100644
--- a/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/.openapi-generator/FILES
@@ -140,6 +140,7 @@ src/Org.OpenAPITools/Client/DateOnlyNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningToken.cs
diff --git a/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/api/openapi.yaml b/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/api/openapi.yaml
index d8106a5755fc..ca451f3fb832 100644
--- a/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/api/openapi.yaml
+++ b/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/api/openapi.yaml
@@ -331,6 +331,40 @@ paths:
       summary: uploads an image
       tags:
       - pet
+  /pet/{petId}/uploadImages:
+    post:
+      description: ""
+      operationId: uploadFiles
+      parameters:
+      - description: ID of pet to update
+        explode: false
+        in: path
+        name: petId
+        required: true
+        schema:
+          format: int64
+          type: integer
+        style: simple
+      requestBody:
+        content:
+          multipart/form-data:
+            schema:
+              $ref: "#/components/schemas/uploadFiles_request"
+        required: true
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ApiResponse"
+          description: successful operation
+      security:
+      - petstore_auth:
+        - write:pets
+        - read:pets
+      summary: uploads an images
+      tags:
+      - pet
   /store/inventory:
     get:
       description: Returns a map of status codes to quantities
@@ -2924,6 +2958,16 @@ components:
           format: binary
           type: string
       type: object
+    uploadFiles_request:
+      properties:
+        files:
+          items:
+            format: binary
+            type: string
+          type: array
+      required:
+      - files
+      type: object
     testEnumParameters_request:
       properties:
         enum_form_string_array:
diff --git a/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/docs/apis/PetApi.md b/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/docs/apis/PetApi.md
index 2826ea00f728..b42ee516b313 100644
--- a/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/docs/apis/PetApi.md
+++ b/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/docs/apis/PetApi.md
@@ -13,6 +13,7 @@ All URIs are relative to *http://petstore.swagger.io:80/v2*
 | [**UpdatePetWithForm**](PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data |
 | [**UploadFile**](PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image |
 | [**UploadFileWithRequiredFile**](PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required) |
+| [**UploadFiles**](PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images |
 
 <a id="addpet"></a>
 # **AddPet**
@@ -341,3 +342,38 @@ uploads an image (required)
 
 [[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
 
+<a id="uploadfiles"></a>
+# **UploadFiles**
+> ApiResponse UploadFiles (List<System.IO.Stream> files, long petId)
+
+uploads an images
+
+
+### Parameters
+
+| Name | Type | Description | Notes |
+|------|------|-------------|-------|
+| **files** | **List&lt;System.IO.Stream&gt;** |  |  |
+| **petId** | **long** | ID of pet to update |  |
+
+### Return type
+
+[**ApiResponse**](ApiResponse.md)
+
+### Authorization
+
+[petstore_auth](../README.md#petstore_auth)
+
+### HTTP request headers
+
+ - **Content-Type**: multipart/form-data
+ - **Accept**: application/json
+
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **200** | successful operation |  -  |
+
+[[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
+
diff --git a/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs b/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
index 406dbc964a6d..d207bb93dc69 100644
--- a/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
@@ -196,7 +196,7 @@ public async Task TestEndpointParametersAsyncTest()
             string patternWithoutDelimiter = default!;
             byte[] varByte = default!;
             double varDouble = default!;
-            Client.Option<System.IO.Stream> binary = default!;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> binary = default!;
             Client.Option<string> callback = default!;
             Client.Option<DateOnly> date = default!;
             Client.Option<DateTime> dateTime = default!;
diff --git a/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/src/Org.OpenAPITools.Test/Api/PetApiTests.cs b/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
index 49e7b21b53c2..6bb1f953987c 100644
--- a/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
@@ -137,7 +137,7 @@ public async Task UploadFileAsyncTest()
         {
             long petId = default!;
             Client.Option<string> additionalMetadata = default!;
-            Client.Option<System.IO.Stream> file = default!;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> file = default!;
             var response = await _instance.UploadFileAsync(petId, additionalMetadata, file);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
@@ -150,11 +150,24 @@ public async Task UploadFileAsyncTest()
         public async Task UploadFileWithRequiredFileAsyncTest()
         {
             long petId = default!;
-            System.IO.Stream requiredFile = default!;
+            Org.OpenAPITools.Client.FileParameter requiredFile = default!;
             Client.Option<string> additionalMetadata = default!;
             var response = await _instance.UploadFileWithRequiredFileAsync(petId, requiredFile, additionalMetadata);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
         }
+
+        /// <summary>
+        /// Test UploadFiles
+        /// </summary>
+        [Fact (Skip = "not implemented")]
+        public async Task UploadFilesAsyncTest()
+        {
+            List<Org.OpenAPITools.Client.FileParameter> files = default!;
+            long petId = default!;
+            var response = await _instance.UploadFilesAsync(files, petId);
+            var model = response.Ok();
+            Assert.IsType<ApiResponse>(model);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/src/Org.OpenAPITools/Api/DefaultApi.cs b/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/src/Org.OpenAPITools/Api/DefaultApi.cs
index 2391c7e1ee03..46b798fe32ca 100644
--- a/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/src/Org.OpenAPITools/Api/DefaultApi.cs
+++ b/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/src/Org.OpenAPITools/Api/DefaultApi.cs
@@ -766,15 +766,12 @@ public async Task<IGetCountryApiResponse> GetCountryAsync(string country, System
                         ? "/country"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/country");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("country", ClientUtils.ParameterToString(country)));
 
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
-
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("country", ClientUtils.ParameterToString(country)));
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
 
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -782,11 +779,6 @@ public async Task<IGetCountryApiResponse> GetCountryAsync(string country, System
                         "application/x-www-form-urlencoded"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/src/Org.OpenAPITools/Api/FakeApi.cs b/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/src/Org.OpenAPITools/Api/FakeApi.cs
index 262a94ef2520..54a1c8c85360 100644
--- a/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/src/Org.OpenAPITools/Api/FakeApi.cs
+++ b/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/src/Org.OpenAPITools/Api/FakeApi.cs
@@ -332,7 +332,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -356,7 +356,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>?&gt;</returns>
-        Task<ITestEndpointParametersApiResponse?> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse?> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// To test enum parameters
@@ -4082,7 +4082,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<System.IO.Stream> binary, ref Option<string> callback, ref Option<DateOnly> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
+        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<Org.OpenAPITools.Client.FileParameter> binary, ref Option<string> callback, ref Option<DateOnly> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
 
         /// <summary>
         /// Validates the request parameters
@@ -4094,7 +4094,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="password"></param>
         /// <param name="varString"></param>
         /// <returns></returns>
-        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<System.IO.Stream> binary, Option<string> callback, Option<string> password, Option<string> varString)
+        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<string> password, Option<string> varString)
         {
             if (patternWithoutDelimiter == null)
                 throw new ArgumentNullException(nameof(patternWithoutDelimiter));
@@ -4133,7 +4133,7 @@ private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLog = false;
             AfterTestEndpointParameters(ref suppressDefaultLog, apiResponseLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4160,7 +4160,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -4182,7 +4182,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorTestEndpointParameters(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4211,7 +4211,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트  Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -4232,7 +4232,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse?> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse?> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -4264,7 +4264,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -4283,51 +4283,48 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         ? "/fake"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("number", ClientUtils.ParameterToString(number)));
 
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("pattern_without_delimiter", ClientUtils.ParameterToString(patternWithoutDelimiter)));
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("byte", ClientUtils.ParameterToString(varByte)));
 
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("number", ClientUtils.ParameterToString(number)));
-
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("pattern_without_delimiter", ClientUtils.ParameterToString(patternWithoutDelimiter)));
-
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("byte", ClientUtils.ParameterToString(varByte)));
-
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("double", ClientUtils.ParameterToString(varDouble)));
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("double", ClientUtils.ParameterToString(varDouble)));
 
                     if (binary.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(binary.Value));
+                        throw new NotSupportedException("File parameters cannot be sent with application/x-www-form-urlencoded. Change the operation's content type to multipart/form-data.");
 
                     if (callback.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("callback", ClientUtils.ParameterToString(callback.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("callback", ClientUtils.ParameterToString(callback.Value)));
 
                     if (date.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("date", ClientUtils.ParameterToString(date.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("date", ClientUtils.ParameterToString(date.Value)));
 
                     if (dateTime.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("dateTime", ClientUtils.ParameterToString(dateTime.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("dateTime", ClientUtils.ParameterToString(dateTime.Value)));
 
                     if (int32.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("int32", ClientUtils.ParameterToString(int32.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("int32", ClientUtils.ParameterToString(int32.Value)));
 
                     if (int64.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("int64", ClientUtils.ParameterToString(int64.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("int64", ClientUtils.ParameterToString(int64.Value)));
 
                     if (integer.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("integer", ClientUtils.ParameterToString(integer.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("integer", ClientUtils.ParameterToString(integer.Value)));
 
                     if (password.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("password", ClientUtils.ParameterToString(password.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("password", ClientUtils.ParameterToString(password.Value)));
 
                     if (varFloat.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("float", ClientUtils.ParameterToString(varFloat.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("float", ClientUtils.ParameterToString(varFloat.Value)));
 
                     if (varString.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("string", ClientUtils.ParameterToString(varString.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("string", ClientUtils.ParameterToString(varString.Value)));
+
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -4342,11 +4339,6 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         "application/x-www-form-urlencoded"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -4639,17 +4631,16 @@ public async Task<ITestEnumParametersApiResponse> TestEnumParametersAsync(Option
                     if (enumHeaderStringArray.IsSet)
                         httpRequestMessageLocalVar.Headers.Add("enum_header_string_array", ClientUtils.ParameterToString(enumHeaderStringArray.Value));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
-
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (enumFormString.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("enum_form_string", ClientUtils.ParameterToString(enumFormString.Value)));
+                    if (enumFormString.IsSet)
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("enum_form_string", ClientUtils.ParameterToString(enumFormString.Value)));
 
                     if (enumFormStringArray.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("enum_form_string_array", ClientUtils.ParameterToString(enumFormStringArray.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("enum_form_string_array", ClientUtils.ParameterToString(enumFormStringArray.Value)));
+
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
 
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -4657,11 +4648,6 @@ public async Task<ITestEnumParametersApiResponse> TestEnumParametersAsync(Option
                         "application/x-www-form-urlencoded"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Get;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -5548,17 +5534,14 @@ public async Task<ITestJsonFormDataApiResponse> TestJsonFormDataAsync(string par
                         ? "/fake/jsonFormData"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/jsonFormData");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("param", ClientUtils.ParameterToString(param)));
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("param2", ClientUtils.ParameterToString(param2)));
 
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("param", ClientUtils.ParameterToString(param)));
-
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("param2", ClientUtils.ParameterToString(param2)));
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
 
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -5566,11 +5549,6 @@ public async Task<ITestJsonFormDataApiResponse> TestJsonFormDataAsync(string par
                         "application/x-www-form-urlencoded"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Get;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/src/Org.OpenAPITools/Api/PetApi.cs b/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/src/Org.OpenAPITools/Api/PetApi.cs
index 2d7e4dab0b84..c5de9cd55ad1 100644
--- a/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/src/Org.OpenAPITools/Api/PetApi.cs
+++ b/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/src/Org.OpenAPITools/Api/PetApi.cs
@@ -218,7 +218,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image
@@ -231,7 +231,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>?&gt;</returns>
-        Task<IUploadFileApiResponse?> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse?> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -245,7 +245,7 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -258,7 +258,32 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>?&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse?> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse?> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>?&gt;</returns>
+        Task<IUploadFilesApiResponse?> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
     }
 
     /// <summary>
@@ -417,6 +442,18 @@ public interface IUploadFileWithRequiredFileApiResponse : Org.OpenAPITools.Clien
         bool IsOk { get; }
     }
 
+    /// <summary>
+    /// The <see cref="IUploadFilesApiResponse"/>
+    /// </summary>
+    public interface IUploadFilesApiResponse : Org.OpenAPITools.Client.IApiResponse, IOk<Org.OpenAPITools.Model.ApiResponse?>
+    {
+        /// <summary>
+        /// Returns true if the response is 200 Ok
+        /// </summary>
+        /// <returns></returns>
+        bool IsOk { get; }
+    }
+
     /// <summary>
     /// Represents a collection of functions to interact with the API endpoints
     /// </summary>
@@ -601,6 +638,26 @@ internal void ExecuteOnErrorUploadFileWithRequiredFile(Exception exception)
         {
             OnErrorUploadFileWithRequiredFile?.Invoke(this, new ExceptionEventArgs(exception));
         }
+
+        /// <summary>
+        /// The event raised after the server response
+        /// </summary>
+        public event EventHandler<ApiResponseEventArgs>? OnUploadFiles;
+
+        /// <summary>
+        /// The event raised after an error querying the server
+        /// </summary>
+        public event EventHandler<ExceptionEventArgs>? OnErrorUploadFiles;
+
+        internal void ExecuteOnUploadFiles(PetApi.UploadFilesApiResponse apiResponse)
+        {
+            OnUploadFiles?.Invoke(this, new ApiResponseEventArgs(apiResponse));
+        }
+
+        internal void ExecuteOnErrorUploadFiles(Exception exception)
+        {
+            OnErrorUploadFiles?.Invoke(this, new ExceptionEventArgs(exception));
+        }
     }
 
     /// <summary>
@@ -2332,17 +2389,16 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (name.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("name", ClientUtils.ParameterToString(name.Value)));
+                    if (name.IsSet)
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("name", ClientUtils.ParameterToString(name.Value)));
 
                     if (status.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("status", ClientUtils.ParameterToString(status.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("status", ClientUtils.ParameterToString(status.Value)));
+
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -2357,11 +2413,6 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         "application/x-www-form-urlencoded"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -2461,7 +2512,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<System.IO.Stream> file);
+        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Validates the request parameters
@@ -2469,7 +2520,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
         /// <returns></returns>
-        private void ValidateUploadFile(Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void ValidateUploadFile(Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             if (additionalMetadata.IsSet && additionalMetadata.Value == null)
                 throw new ArgumentNullException(nameof(additionalMetadata));
@@ -2485,7 +2536,7 @@ private void ValidateUploadFile(Option<string> additionalMetadata, Option<System
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLog = false;
             AfterUploadFile(ref suppressDefaultLog, apiResponseLocalVar, petId, additionalMetadata, file);
@@ -2501,7 +2552,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2512,7 +2563,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, additionalMetadata, file);
@@ -2530,7 +2581,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// uploads an image 
@@ -2540,7 +2591,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse?> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse?> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2561,7 +2612,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2581,17 +2632,23 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImage");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (additionalMetadata.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
+                    if (additionalMetadata.IsSet)
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
 
                     if (file.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(file.Value));
+                    {
+                        var streamContentLocalVar = new StreamContent(file.Value.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "file", file.Value.FileName ?? "file");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -2606,11 +2663,6 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         "multipart/form-data"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json"
                     };
@@ -2751,7 +2803,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFileWithRequiredFile(ref long petId, ref System.IO.Stream requiredFile, ref Option<string> additionalMetadata);
+        partial void FormatUploadFileWithRequiredFile(ref long petId, ref Org.OpenAPITools.Client.FileParameter requiredFile, ref Option<string> additionalMetadata);
 
         /// <summary>
         /// Validates the request parameters
@@ -2759,7 +2811,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
         /// <returns></returns>
-        private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void ValidateUploadFileWithRequiredFile(Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             if (requiredFile == null)
                 throw new ArgumentNullException(nameof(requiredFile));
@@ -2775,7 +2827,7 @@ private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, O
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLog = false;
             AfterUploadFileWithRequiredFile(ref suppressDefaultLog, apiResponseLocalVar, petId, requiredFile, additionalMetadata);
@@ -2791,7 +2843,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2802,7 +2854,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFileWithRequiredFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, requiredFile, additionalMetadata);
@@ -2820,7 +2872,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// uploads an image (required) 
@@ -2830,7 +2882,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse?> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse?> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2851,7 +2903,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2871,16 +2923,22 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/{petId}/uploadImageWithRequiredFile");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    multipartContentLocalVar.Add(new StreamContent(requiredFile));
+                    {
+                        var streamContentLocalVar = new StreamContent(requiredFile.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "requiredFile", requiredFile.FileName ?? "requiredFile");
+                    }
 
                     if (additionalMetadata.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -2895,11 +2953,6 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         "multipart/form-data"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json",
                         "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
@@ -3040,5 +3093,283 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
 
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
+
+        partial void FormatUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files, ref long petId);
+
+        /// <summary>
+        /// Validates the request parameters
+        /// </summary>
+        /// <param name="files"></param>
+        /// <returns></returns>
+        private void ValidateUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files)
+        {
+            if (files == null)
+                throw new ArgumentNullException(nameof(files));
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void AfterUploadFilesDefaultImplementation(IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLog = false;
+            AfterUploadFiles(ref suppressDefaultLog, apiResponseLocalVar, files, petId);
+            if (!suppressDefaultLog)
+                Logger.LogInformation("{0,-9} | {1} | {2}", (apiResponseLocalVar.DownloadedAt - apiResponseLocalVar.RequestedAt).TotalSeconds, apiResponseLocalVar.StatusCode, apiResponseLocalVar.Path);
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="suppressDefaultLog"></param>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void AfterUploadFiles(ref bool suppressDefaultLog, IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// Logs exceptions that occur while retrieving the server response
+        /// </summary>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void OnErrorUploadFilesDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLogLocalVar = false;
+            OnErrorUploadFiles(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, files, petId);
+            if (!suppressDefaultLogLocalVar)
+                Logger.LogError(exceptionLocalVar, "An error occurred while sending the request to the server.");
+        }
+
+        /// <summary>
+        /// A partial method that gives developers a way to provide customized exception handling
+        /// </summary>
+        /// <param name="suppressDefaultLogLocalVar"></param>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void OnErrorUploadFiles(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse?> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            try
+            {
+                return await UploadFilesAsync(files, petId, cancellationToken).ConfigureAwait(false);
+            }
+            catch (Exception)
+            {
+                return null;
+            }
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            UriBuilder uriBuilderLocalVar = new UriBuilder();
+
+            try
+            {
+                ValidateUploadFiles(files);
+
+                FormatUploadFiles(files, ref petId);
+
+                using (HttpRequestMessage httpRequestMessageLocalVar = new HttpRequestMessage())
+                {
+                    uriBuilderLocalVar.Host = HttpClient.BaseAddress!.Host;
+                    uriBuilderLocalVar.Port = HttpClient.BaseAddress.Port;
+                    uriBuilderLocalVar.Scheme = HttpClient.BaseAddress.Scheme;
+                    uriBuilderLocalVar.Path = HttpClient.BaseAddress.AbsolutePath == "/"
+                        ? "/pet/{petId}/uploadImages"
+                        : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImages");
+                    uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
+
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
+
+                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
+
+                    foreach (Org.OpenAPITools.Client.FileParameter fileParameterLocalVar in files)
+                    {
+                        var streamContentLocalVar = new StreamContent(fileParameterLocalVar.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "files", fileParameterLocalVar.FileName ?? "files");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
+
+                    List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
+                    httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
+
+                    OAuthToken oauthTokenLocalVar1 = (OAuthToken) await OauthTokenProvider.GetAsync(cancellation: cancellationToken).ConfigureAwait(false);
+
+                    tokenBaseLocalVars.Add(oauthTokenLocalVar1);
+
+                    oauthTokenLocalVar1.UseInHeader(httpRequestMessageLocalVar, "");
+
+                    string[] contentTypes = new string[] {
+                        "multipart/form-data"
+                    };
+
+                    string[] acceptLocalVars = new string[] {
+                        "application/json"
+                    };
+
+                    IEnumerable<MediaTypeWithQualityHeaderValue> acceptHeaderValuesLocalVar = ClientUtils.SelectHeaderAcceptArray(acceptLocalVars);
+
+                    foreach (var acceptLocalVar in acceptHeaderValuesLocalVar)
+                        httpRequestMessageLocalVar.Headers.Accept.Add(acceptLocalVar);
+
+                    httpRequestMessageLocalVar.Method = HttpMethod.Post;
+
+                    DateTime requestedAtLocalVar = DateTime.UtcNow;
+
+                    using (HttpResponseMessage httpResponseMessageLocalVar = await HttpClient.SendAsync(httpRequestMessageLocalVar, cancellationToken).ConfigureAwait(false))
+                    {
+                        ILogger<UploadFilesApiResponse> apiResponseLoggerLocalVar = LoggerFactory.CreateLogger<UploadFilesApiResponse>();
+                        UploadFilesApiResponse apiResponseLocalVar;
+
+                        switch ((int)httpResponseMessageLocalVar.StatusCode) {
+                            default: {
+                                string responseContentLocalVar = await httpResponseMessageLocalVar.Content.ReadAsStringAsync(cancellationToken).ConfigureAwait(false);
+                                apiResponseLocalVar = new(apiResponseLoggerLocalVar, httpRequestMessageLocalVar, httpResponseMessageLocalVar, responseContentLocalVar, "/pet/{petId}/uploadImages", requestedAtLocalVar, _jsonSerializerOptions);
+
+                                break;
+                            }
+                        }
+
+                        AfterUploadFilesDefaultImplementation(apiResponseLocalVar, files, petId);
+
+                        Events.ExecuteOnUploadFiles(apiResponseLocalVar);
+
+                        if (apiResponseLocalVar.StatusCode == (HttpStatusCode) 429)
+                            foreach(TokenBase tokenBaseLocalVar in tokenBaseLocalVars)
+                                tokenBaseLocalVar.BeginRateLimit();
+
+                        return apiResponseLocalVar;
+                    }
+                }
+            }
+            catch(Exception e)
+            {
+                OnErrorUploadFilesDefaultImplementation(e, "/pet/{petId}/uploadImages", uriBuilderLocalVar.Path, files, petId);
+                Events.ExecuteOnErrorUploadFiles(e);
+                throw;
+            }
+        }
+
+        /// <summary>
+        /// The <see cref="UploadFilesApiResponse"/>
+        /// </summary>
+        public partial class UploadFilesApiResponse : Org.OpenAPITools.Client.ApiResponse, IUploadFilesApiResponse
+        {
+            /// <summary>
+            /// The logger
+            /// </summary>
+            public ILogger<UploadFilesApiResponse> Logger { get; }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="rawContent"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, string rawContent, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, rawContent, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="contentStream"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, System.IO.Stream contentStream, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, contentStream, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            partial void OnCreated(global::System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage);
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public bool IsOk => 200 == (int)StatusCode;
+
+            /// <summary>
+            /// Deserializes the response if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public Org.OpenAPITools.Model.ApiResponse? Ok()
+            {
+                // This logic may be modified with the AsModel.mustache template
+                return IsOk
+                    ? System.Text.Json.JsonSerializer.Deserialize<Org.OpenAPITools.Model.ApiResponse>(RawContent, _jsonSerializerOptions)
+                    : null;
+            }
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok and the deserialized response is not null
+            /// </summary>
+            /// <param name="result"></param>
+            /// <returns></returns>
+            public bool TryOk([NotNullWhen(true)]out Org.OpenAPITools.Model.ApiResponse? result)
+            {
+                result = null;
+
+                try
+                {
+                    result = Ok();
+                } catch (Exception e)
+                {
+                    OnDeserializationErrorDefaultImplementation(e, (HttpStatusCode)200);
+                }
+
+                return result != null;
+            }
+
+            private void OnDeserializationErrorDefaultImplementation(Exception exception, HttpStatusCode httpStatusCode)
+            {
+                bool suppressDefaultLog = false;
+                OnDeserializationError(ref suppressDefaultLog, exception, httpStatusCode);
+                if (!suppressDefaultLog)
+                    Logger.LogError(exception, "An error occurred while deserializing the {code} response.", httpStatusCode);
+            }
+
+            partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..77779fe7d75a
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,42 @@
+// <auto-generated>
+/*
+ * OpenAPI Petstore
+ *
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+#nullable enable
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string? FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string? fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net10/OneOf/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net10/OneOf/.openapi-generator/FILES
index a36efde4422e..cfb76c7ed0ac 100644
--- a/samples/client/petstore/csharp/generichost/net10/OneOf/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net10/OneOf/.openapi-generator/FILES
@@ -26,6 +26,7 @@ src/Org.OpenAPITools/Client/DateOnlyNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/JsonSerializerOptionsProvider.cs
 src/Org.OpenAPITools/Client/Option.cs
diff --git a/samples/client/petstore/csharp/generichost/net10/OneOf/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net10/OneOf/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..e629f4afdaec
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net10/OneOf/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,42 @@
+// <auto-generated>
+/*
+ * fruity
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * The version of the OpenAPI document: 0.0.1
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+#nullable enable
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string? FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string? fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net10/Petstore/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net10/Petstore/.openapi-generator/FILES
index ab28c754b4b1..a3e02b328e0a 100644
--- a/samples/client/petstore/csharp/generichost/net10/Petstore/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net10/Petstore/.openapi-generator/FILES
@@ -140,6 +140,7 @@ src/Org.OpenAPITools/Client/DateOnlyNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningToken.cs
diff --git a/samples/client/petstore/csharp/generichost/net10/Petstore/api/openapi.yaml b/samples/client/petstore/csharp/generichost/net10/Petstore/api/openapi.yaml
index d8106a5755fc..ca451f3fb832 100644
--- a/samples/client/petstore/csharp/generichost/net10/Petstore/api/openapi.yaml
+++ b/samples/client/petstore/csharp/generichost/net10/Petstore/api/openapi.yaml
@@ -331,6 +331,40 @@ paths:
       summary: uploads an image
       tags:
       - pet
+  /pet/{petId}/uploadImages:
+    post:
+      description: ""
+      operationId: uploadFiles
+      parameters:
+      - description: ID of pet to update
+        explode: false
+        in: path
+        name: petId
+        required: true
+        schema:
+          format: int64
+          type: integer
+        style: simple
+      requestBody:
+        content:
+          multipart/form-data:
+            schema:
+              $ref: "#/components/schemas/uploadFiles_request"
+        required: true
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ApiResponse"
+          description: successful operation
+      security:
+      - petstore_auth:
+        - write:pets
+        - read:pets
+      summary: uploads an images
+      tags:
+      - pet
   /store/inventory:
     get:
       description: Returns a map of status codes to quantities
@@ -2924,6 +2958,16 @@ components:
           format: binary
           type: string
       type: object
+    uploadFiles_request:
+      properties:
+        files:
+          items:
+            format: binary
+            type: string
+          type: array
+      required:
+      - files
+      type: object
     testEnumParameters_request:
       properties:
         enum_form_string_array:
diff --git a/samples/client/petstore/csharp/generichost/net10/Petstore/docs/apis/PetApi.md b/samples/client/petstore/csharp/generichost/net10/Petstore/docs/apis/PetApi.md
index 2826ea00f728..b42ee516b313 100644
--- a/samples/client/petstore/csharp/generichost/net10/Petstore/docs/apis/PetApi.md
+++ b/samples/client/petstore/csharp/generichost/net10/Petstore/docs/apis/PetApi.md
@@ -13,6 +13,7 @@ All URIs are relative to *http://petstore.swagger.io:80/v2*
 | [**UpdatePetWithForm**](PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data |
 | [**UploadFile**](PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image |
 | [**UploadFileWithRequiredFile**](PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required) |
+| [**UploadFiles**](PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images |
 
 <a id="addpet"></a>
 # **AddPet**
@@ -341,3 +342,38 @@ uploads an image (required)
 
 [[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
 
+<a id="uploadfiles"></a>
+# **UploadFiles**
+> ApiResponse UploadFiles (List<System.IO.Stream> files, long petId)
+
+uploads an images
+
+
+### Parameters
+
+| Name | Type | Description | Notes |
+|------|------|-------------|-------|
+| **files** | **List&lt;System.IO.Stream&gt;** |  |  |
+| **petId** | **long** | ID of pet to update |  |
+
+### Return type
+
+[**ApiResponse**](ApiResponse.md)
+
+### Authorization
+
+[petstore_auth](../README.md#petstore_auth)
+
+### HTTP request headers
+
+ - **Content-Type**: multipart/form-data
+ - **Accept**: application/json
+
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **200** | successful operation |  -  |
+
+[[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
+
diff --git a/samples/client/petstore/csharp/generichost/net10/Petstore/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs b/samples/client/petstore/csharp/generichost/net10/Petstore/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
index 66769b3aee6a..fed093fb206f 100644
--- a/samples/client/petstore/csharp/generichost/net10/Petstore/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/net10/Petstore/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
@@ -196,7 +196,7 @@ public async Task TestEndpointParametersAsyncTest()
             string patternWithoutDelimiter = default;
             byte[] varByte = default;
             double varDouble = default;
-            Client.Option<System.IO.Stream> binary = default;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> binary = default;
             Client.Option<string> callback = default;
             Client.Option<DateOnly> date = default;
             Client.Option<DateTime> dateTime = default;
diff --git a/samples/client/petstore/csharp/generichost/net10/Petstore/src/Org.OpenAPITools.Test/Api/PetApiTests.cs b/samples/client/petstore/csharp/generichost/net10/Petstore/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
index 215e88093797..e9b05337bb59 100644
--- a/samples/client/petstore/csharp/generichost/net10/Petstore/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/net10/Petstore/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
@@ -137,7 +137,7 @@ public async Task UploadFileAsyncTest()
         {
             long petId = default;
             Client.Option<string> additionalMetadata = default;
-            Client.Option<System.IO.Stream> file = default;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> file = default;
             var response = await _instance.UploadFileAsync(petId, additionalMetadata, file);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
@@ -150,11 +150,24 @@ public async Task UploadFileAsyncTest()
         public async Task UploadFileWithRequiredFileAsyncTest()
         {
             long petId = default;
-            System.IO.Stream requiredFile = default;
+            Org.OpenAPITools.Client.FileParameter requiredFile = default;
             Client.Option<string> additionalMetadata = default;
             var response = await _instance.UploadFileWithRequiredFileAsync(petId, requiredFile, additionalMetadata);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
         }
+
+        /// <summary>
+        /// Test UploadFiles
+        /// </summary>
+        [Fact (Skip = "not implemented")]
+        public async Task UploadFilesAsyncTest()
+        {
+            List<Org.OpenAPITools.Client.FileParameter> files = default;
+            long petId = default;
+            var response = await _instance.UploadFilesAsync(files, petId);
+            var model = response.Ok();
+            Assert.IsType<ApiResponse>(model);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/net10/Petstore/src/Org.OpenAPITools/Api/DefaultApi.cs b/samples/client/petstore/csharp/generichost/net10/Petstore/src/Org.OpenAPITools/Api/DefaultApi.cs
index 3c26a27185e6..44d52e7e1090 100644
--- a/samples/client/petstore/csharp/generichost/net10/Petstore/src/Org.OpenAPITools/Api/DefaultApi.cs
+++ b/samples/client/petstore/csharp/generichost/net10/Petstore/src/Org.OpenAPITools/Api/DefaultApi.cs
@@ -764,27 +764,19 @@ public async Task<IGetCountryApiResponse> GetCountryAsync(string country, System
                         ? "/country"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/country");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("country", ClientUtils.ParameterToString(country)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/net10/Petstore/src/Org.OpenAPITools/Api/FakeApi.cs b/samples/client/petstore/csharp/generichost/net10/Petstore/src/Org.OpenAPITools/Api/FakeApi.cs
index 01aaf0ccbd85..482421f8c4ea 100644
--- a/samples/client/petstore/csharp/generichost/net10/Petstore/src/Org.OpenAPITools/Api/FakeApi.cs
+++ b/samples/client/petstore/csharp/generichost/net10/Petstore/src/Org.OpenAPITools/Api/FakeApi.cs
@@ -330,7 +330,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -354,7 +354,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// To test enum parameters
@@ -4080,7 +4080,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<System.IO.Stream> binary, ref Option<string> callback, ref Option<DateOnly> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
+        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<Org.OpenAPITools.Client.FileParameter> binary, ref Option<string> callback, ref Option<DateOnly> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
 
         /// <summary>
         /// Validates the request parameters
@@ -4092,7 +4092,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="password"></param>
         /// <param name="varString"></param>
         /// <returns></returns>
-        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<System.IO.Stream> binary, Option<string> callback, Option<string> password, Option<string> varString)
+        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<string> password, Option<string> varString)
         {
             if (patternWithoutDelimiter == null)
                 throw new ArgumentNullException(nameof(patternWithoutDelimiter));
@@ -4131,7 +4131,7 @@ private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLog = false;
             AfterTestEndpointParameters(ref suppressDefaultLog, apiResponseLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4158,7 +4158,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -4180,7 +4180,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorTestEndpointParameters(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4209,7 +4209,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트  Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -4230,7 +4230,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -4262,7 +4262,7 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDe
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -4281,14 +4281,8 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         ? "/fake"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("number", ClientUtils.ParameterToString(number)));
 
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("pattern_without_delimiter", ClientUtils.ParameterToString(patternWithoutDelimiter)));
@@ -4298,7 +4292,7 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("double", ClientUtils.ParameterToString(varDouble)));
 
                     if (binary.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(binary.Value));
+                        throw new NotSupportedException("File parameters cannot be sent with application/x-www-form-urlencoded. Change the operation's content type to multipart/form-data.");
 
                     if (callback.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("callback", ClientUtils.ParameterToString(callback.Value)));
@@ -4327,6 +4321,9 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                     if (varString.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("string", ClientUtils.ParameterToString(varString.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -4340,11 +4337,6 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -4637,29 +4629,23 @@ public async Task<ITestEnumParametersApiResponse> TestEnumParametersAsync(Option
                     if (enumHeaderStringArray.IsSet)
                         httpRequestMessageLocalVar.Headers.Add("enum_header_string_array", ClientUtils.ParameterToString(enumHeaderStringArray.Value));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (enumFormString.IsSet)
+                    if (enumFormString.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("enum_form_string", ClientUtils.ParameterToString(enumFormString.Value)));
 
                     if (enumFormStringArray.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("enum_form_string_array", ClientUtils.ParameterToString(enumFormStringArray.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Get;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -5546,29 +5532,21 @@ public async Task<ITestJsonFormDataApiResponse> TestJsonFormDataAsync(string par
                         ? "/fake/jsonFormData"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/jsonFormData");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("param", ClientUtils.ParameterToString(param)));
 
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("param2", ClientUtils.ParameterToString(param2)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Get;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/net10/Petstore/src/Org.OpenAPITools/Api/PetApi.cs b/samples/client/petstore/csharp/generichost/net10/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
index a1817e3df697..da4dfd225bc4 100644
--- a/samples/client/petstore/csharp/generichost/net10/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
+++ b/samples/client/petstore/csharp/generichost/net10/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
@@ -216,7 +216,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image
@@ -229,7 +229,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -243,7 +243,7 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -256,7 +256,32 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        Task<IUploadFilesApiResponse> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
     }
 
     /// <summary>
@@ -415,6 +440,18 @@ public interface IUploadFileWithRequiredFileApiResponse : Org.OpenAPITools.Clien
         bool IsOk { get; }
     }
 
+    /// <summary>
+    /// The <see cref="IUploadFilesApiResponse"/>
+    /// </summary>
+    public interface IUploadFilesApiResponse : Org.OpenAPITools.Client.IApiResponse, IOk<Org.OpenAPITools.Model.ApiResponse>
+    {
+        /// <summary>
+        /// Returns true if the response is 200 Ok
+        /// </summary>
+        /// <returns></returns>
+        bool IsOk { get; }
+    }
+
     /// <summary>
     /// Represents a collection of functions to interact with the API endpoints
     /// </summary>
@@ -599,6 +636,26 @@ internal void ExecuteOnErrorUploadFileWithRequiredFile(Exception exception)
         {
             OnErrorUploadFileWithRequiredFile?.Invoke(this, new ExceptionEventArgs(exception));
         }
+
+        /// <summary>
+        /// The event raised after the server response
+        /// </summary>
+        public event EventHandler<ApiResponseEventArgs> OnUploadFiles;
+
+        /// <summary>
+        /// The event raised after an error querying the server
+        /// </summary>
+        public event EventHandler<ExceptionEventArgs> OnErrorUploadFiles;
+
+        internal void ExecuteOnUploadFiles(PetApi.UploadFilesApiResponse apiResponse)
+        {
+            OnUploadFiles?.Invoke(this, new ApiResponseEventArgs(apiResponse));
+        }
+
+        internal void ExecuteOnErrorUploadFiles(Exception exception)
+        {
+            OnErrorUploadFiles?.Invoke(this, new ExceptionEventArgs(exception));
+        }
     }
 
     /// <summary>
@@ -2330,18 +2387,17 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (name.IsSet)
+                    if (name.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("name", ClientUtils.ParameterToString(name.Value)));
 
                     if (status.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("status", ClientUtils.ParameterToString(status.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -2355,11 +2411,6 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -2459,7 +2510,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<System.IO.Stream> file);
+        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Validates the request parameters
@@ -2467,7 +2518,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
         /// <returns></returns>
-        private void ValidateUploadFile(Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void ValidateUploadFile(Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             if (additionalMetadata.IsSet && additionalMetadata.Value == null)
                 throw new ArgumentNullException(nameof(additionalMetadata));
@@ -2483,7 +2534,7 @@ private void ValidateUploadFile(Option<string> additionalMetadata, Option<System
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLog = false;
             AfterUploadFile(ref suppressDefaultLog, apiResponseLocalVar, petId, additionalMetadata, file);
@@ -2499,7 +2550,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2510,7 +2561,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, additionalMetadata, file);
@@ -2528,7 +2579,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// uploads an image 
@@ -2538,7 +2589,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2559,7 +2610,7 @@ public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, O
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2579,17 +2630,23 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImage");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (additionalMetadata.IsSet)
+                    if (additionalMetadata.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
 
                     if (file.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(file.Value));
+                    {
+                        var streamContentLocalVar = new StreamContent(file.Value.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "file", file.Value.FileName ?? "file");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -2604,11 +2661,6 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         "multipart/form-data"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json"
                     };
@@ -2749,7 +2801,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFileWithRequiredFile(ref long petId, ref System.IO.Stream requiredFile, ref Option<string> additionalMetadata);
+        partial void FormatUploadFileWithRequiredFile(ref long petId, ref Org.OpenAPITools.Client.FileParameter requiredFile, ref Option<string> additionalMetadata);
 
         /// <summary>
         /// Validates the request parameters
@@ -2757,7 +2809,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
         /// <returns></returns>
-        private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void ValidateUploadFileWithRequiredFile(Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             if (requiredFile == null)
                 throw new ArgumentNullException(nameof(requiredFile));
@@ -2773,7 +2825,7 @@ private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, O
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLog = false;
             AfterUploadFileWithRequiredFile(ref suppressDefaultLog, apiResponseLocalVar, petId, requiredFile, additionalMetadata);
@@ -2789,7 +2841,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2800,7 +2852,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFileWithRequiredFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, requiredFile, additionalMetadata);
@@ -2818,7 +2870,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// uploads an image (required) 
@@ -2828,7 +2880,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2849,7 +2901,7 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2869,17 +2921,23 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/{petId}/uploadImageWithRequiredFile");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    multipartContentLocalVar.Add(new StreamContent(requiredFile));
+                    {
+                        var streamContentLocalVar = new StreamContent(requiredFile.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "requiredFile", requiredFile.FileName ?? "requiredFile");
+                    }
 
                     if (additionalMetadata.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
 
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -2893,11 +2951,6 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         "multipart/form-data"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json",
                         "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
@@ -3038,5 +3091,283 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
 
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
+
+        partial void FormatUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files, ref long petId);
+
+        /// <summary>
+        /// Validates the request parameters
+        /// </summary>
+        /// <param name="files"></param>
+        /// <returns></returns>
+        private void ValidateUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files)
+        {
+            if (files == null)
+                throw new ArgumentNullException(nameof(files));
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void AfterUploadFilesDefaultImplementation(IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLog = false;
+            AfterUploadFiles(ref suppressDefaultLog, apiResponseLocalVar, files, petId);
+            if (!suppressDefaultLog)
+                Logger.LogInformation("{0,-9} | {1} | {2}", (apiResponseLocalVar.DownloadedAt - apiResponseLocalVar.RequestedAt).TotalSeconds, apiResponseLocalVar.StatusCode, apiResponseLocalVar.Path);
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="suppressDefaultLog"></param>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void AfterUploadFiles(ref bool suppressDefaultLog, IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// Logs exceptions that occur while retrieving the server response
+        /// </summary>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void OnErrorUploadFilesDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLogLocalVar = false;
+            OnErrorUploadFiles(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, files, petId);
+            if (!suppressDefaultLogLocalVar)
+                Logger.LogError(exceptionLocalVar, "An error occurred while sending the request to the server.");
+        }
+
+        /// <summary>
+        /// A partial method that gives developers a way to provide customized exception handling
+        /// </summary>
+        /// <param name="suppressDefaultLogLocalVar"></param>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void OnErrorUploadFiles(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            try
+            {
+                return await UploadFilesAsync(files, petId, cancellationToken).ConfigureAwait(false);
+            }
+            catch (Exception)
+            {
+                return null;
+            }
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            UriBuilder uriBuilderLocalVar = new UriBuilder();
+
+            try
+            {
+                ValidateUploadFiles(files);
+
+                FormatUploadFiles(files, ref petId);
+
+                using (HttpRequestMessage httpRequestMessageLocalVar = new HttpRequestMessage())
+                {
+                    uriBuilderLocalVar.Host = HttpClient.BaseAddress.Host;
+                    uriBuilderLocalVar.Port = HttpClient.BaseAddress.Port;
+                    uriBuilderLocalVar.Scheme = HttpClient.BaseAddress.Scheme;
+                    uriBuilderLocalVar.Path = HttpClient.BaseAddress.AbsolutePath == "/"
+                        ? "/pet/{petId}/uploadImages"
+                        : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImages");
+                    uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
+
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
+
+                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+
+                    List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
+
+                    foreach (Org.OpenAPITools.Client.FileParameter fileParameterLocalVar in files)
+                    {
+                        var streamContentLocalVar = new StreamContent(fileParameterLocalVar.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "files", fileParameterLocalVar.FileName ?? "files");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
+
+                    List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
+                    httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
+
+                    OAuthToken oauthTokenLocalVar1 = (OAuthToken) await OauthTokenProvider.GetAsync(cancellation: cancellationToken).ConfigureAwait(false);
+
+                    tokenBaseLocalVars.Add(oauthTokenLocalVar1);
+
+                    oauthTokenLocalVar1.UseInHeader(httpRequestMessageLocalVar, "");
+
+                    string[] contentTypes = new string[] {
+                        "multipart/form-data"
+                    };
+
+                    string[] acceptLocalVars = new string[] {
+                        "application/json"
+                    };
+
+                    IEnumerable<MediaTypeWithQualityHeaderValue> acceptHeaderValuesLocalVar = ClientUtils.SelectHeaderAcceptArray(acceptLocalVars);
+
+                    foreach (var acceptLocalVar in acceptHeaderValuesLocalVar)
+                        httpRequestMessageLocalVar.Headers.Accept.Add(acceptLocalVar);
+
+                    httpRequestMessageLocalVar.Method = HttpMethod.Post;
+
+                    DateTime requestedAtLocalVar = DateTime.UtcNow;
+
+                    using (HttpResponseMessage httpResponseMessageLocalVar = await HttpClient.SendAsync(httpRequestMessageLocalVar, cancellationToken).ConfigureAwait(false))
+                    {
+                        ILogger<UploadFilesApiResponse> apiResponseLoggerLocalVar = LoggerFactory.CreateLogger<UploadFilesApiResponse>();
+                        UploadFilesApiResponse apiResponseLocalVar;
+
+                        switch ((int)httpResponseMessageLocalVar.StatusCode) {
+                            default: {
+                                string responseContentLocalVar = await httpResponseMessageLocalVar.Content.ReadAsStringAsync(cancellationToken).ConfigureAwait(false);
+                                apiResponseLocalVar = new(apiResponseLoggerLocalVar, httpRequestMessageLocalVar, httpResponseMessageLocalVar, responseContentLocalVar, "/pet/{petId}/uploadImages", requestedAtLocalVar, _jsonSerializerOptions);
+
+                                break;
+                            }
+                        }
+
+                        AfterUploadFilesDefaultImplementation(apiResponseLocalVar, files, petId);
+
+                        Events.ExecuteOnUploadFiles(apiResponseLocalVar);
+
+                        if (apiResponseLocalVar.StatusCode == (HttpStatusCode) 429)
+                            foreach(TokenBase tokenBaseLocalVar in tokenBaseLocalVars)
+                                tokenBaseLocalVar.BeginRateLimit();
+
+                        return apiResponseLocalVar;
+                    }
+                }
+            }
+            catch(Exception e)
+            {
+                OnErrorUploadFilesDefaultImplementation(e, "/pet/{petId}/uploadImages", uriBuilderLocalVar.Path, files, petId);
+                Events.ExecuteOnErrorUploadFiles(e);
+                throw;
+            }
+        }
+
+        /// <summary>
+        /// The <see cref="UploadFilesApiResponse"/>
+        /// </summary>
+        public partial class UploadFilesApiResponse : Org.OpenAPITools.Client.ApiResponse, IUploadFilesApiResponse
+        {
+            /// <summary>
+            /// The logger
+            /// </summary>
+            public ILogger<UploadFilesApiResponse> Logger { get; }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="rawContent"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, string rawContent, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, rawContent, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="contentStream"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, System.IO.Stream contentStream, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, contentStream, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            partial void OnCreated(global::System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage);
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public bool IsOk => 200 == (int)StatusCode;
+
+            /// <summary>
+            /// Deserializes the response if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public Org.OpenAPITools.Model.ApiResponse Ok()
+            {
+                // This logic may be modified with the AsModel.mustache template
+                return IsOk
+                    ? System.Text.Json.JsonSerializer.Deserialize<Org.OpenAPITools.Model.ApiResponse>(RawContent, _jsonSerializerOptions)
+                    : null;
+            }
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok and the deserialized response is not null
+            /// </summary>
+            /// <param name="result"></param>
+            /// <returns></returns>
+            public bool TryOk([NotNullWhen(true)]out Org.OpenAPITools.Model.ApiResponse result)
+            {
+                result = null;
+
+                try
+                {
+                    result = Ok();
+                } catch (Exception e)
+                {
+                    OnDeserializationErrorDefaultImplementation(e, (HttpStatusCode)200);
+                }
+
+                return result != null;
+            }
+
+            private void OnDeserializationErrorDefaultImplementation(Exception exception, HttpStatusCode httpStatusCode)
+            {
+                bool suppressDefaultLog = false;
+                OnDeserializationError(ref suppressDefaultLog, exception, httpStatusCode);
+                if (!suppressDefaultLog)
+                    Logger.LogError(exception, "An error occurred while deserializing the {code} response.", httpStatusCode);
+            }
+
+            partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/net10/Petstore/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net10/Petstore/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..6150dbcf4774
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net10/Petstore/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,40 @@
+// <auto-generated>
+/*
+ * OpenAPI Petstore
+ *
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net10/SourceGeneration/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net10/SourceGeneration/.openapi-generator/FILES
index ab28c754b4b1..a3e02b328e0a 100644
--- a/samples/client/petstore/csharp/generichost/net10/SourceGeneration/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net10/SourceGeneration/.openapi-generator/FILES
@@ -140,6 +140,7 @@ src/Org.OpenAPITools/Client/DateOnlyNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningToken.cs
diff --git a/samples/client/petstore/csharp/generichost/net10/SourceGeneration/api/openapi.yaml b/samples/client/petstore/csharp/generichost/net10/SourceGeneration/api/openapi.yaml
index d8106a5755fc..ca451f3fb832 100644
--- a/samples/client/petstore/csharp/generichost/net10/SourceGeneration/api/openapi.yaml
+++ b/samples/client/petstore/csharp/generichost/net10/SourceGeneration/api/openapi.yaml
@@ -331,6 +331,40 @@ paths:
       summary: uploads an image
       tags:
       - pet
+  /pet/{petId}/uploadImages:
+    post:
+      description: ""
+      operationId: uploadFiles
+      parameters:
+      - description: ID of pet to update
+        explode: false
+        in: path
+        name: petId
+        required: true
+        schema:
+          format: int64
+          type: integer
+        style: simple
+      requestBody:
+        content:
+          multipart/form-data:
+            schema:
+              $ref: "#/components/schemas/uploadFiles_request"
+        required: true
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ApiResponse"
+          description: successful operation
+      security:
+      - petstore_auth:
+        - write:pets
+        - read:pets
+      summary: uploads an images
+      tags:
+      - pet
   /store/inventory:
     get:
       description: Returns a map of status codes to quantities
@@ -2924,6 +2958,16 @@ components:
           format: binary
           type: string
       type: object
+    uploadFiles_request:
+      properties:
+        files:
+          items:
+            format: binary
+            type: string
+          type: array
+      required:
+      - files
+      type: object
     testEnumParameters_request:
       properties:
         enum_form_string_array:
diff --git a/samples/client/petstore/csharp/generichost/net10/SourceGeneration/docs/apis/PetApi.md b/samples/client/petstore/csharp/generichost/net10/SourceGeneration/docs/apis/PetApi.md
index 2826ea00f728..b42ee516b313 100644
--- a/samples/client/petstore/csharp/generichost/net10/SourceGeneration/docs/apis/PetApi.md
+++ b/samples/client/petstore/csharp/generichost/net10/SourceGeneration/docs/apis/PetApi.md
@@ -13,6 +13,7 @@ All URIs are relative to *http://petstore.swagger.io:80/v2*
 | [**UpdatePetWithForm**](PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data |
 | [**UploadFile**](PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image |
 | [**UploadFileWithRequiredFile**](PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required) |
+| [**UploadFiles**](PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images |
 
 <a id="addpet"></a>
 # **AddPet**
@@ -341,3 +342,38 @@ uploads an image (required)
 
 [[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
 
+<a id="uploadfiles"></a>
+# **UploadFiles**
+> ApiResponse UploadFiles (List<System.IO.Stream> files, long petId)
+
+uploads an images
+
+
+### Parameters
+
+| Name | Type | Description | Notes |
+|------|------|-------------|-------|
+| **files** | **List&lt;System.IO.Stream&gt;** |  |  |
+| **petId** | **long** | ID of pet to update |  |
+
+### Return type
+
+[**ApiResponse**](ApiResponse.md)
+
+### Authorization
+
+[petstore_auth](../README.md#petstore_auth)
+
+### HTTP request headers
+
+ - **Content-Type**: multipart/form-data
+ - **Accept**: application/json
+
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **200** | successful operation |  -  |
+
+[[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
+
diff --git a/samples/client/petstore/csharp/generichost/net10/SourceGeneration/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs b/samples/client/petstore/csharp/generichost/net10/SourceGeneration/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
index 406dbc964a6d..d207bb93dc69 100644
--- a/samples/client/petstore/csharp/generichost/net10/SourceGeneration/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/net10/SourceGeneration/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
@@ -196,7 +196,7 @@ public async Task TestEndpointParametersAsyncTest()
             string patternWithoutDelimiter = default!;
             byte[] varByte = default!;
             double varDouble = default!;
-            Client.Option<System.IO.Stream> binary = default!;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> binary = default!;
             Client.Option<string> callback = default!;
             Client.Option<DateOnly> date = default!;
             Client.Option<DateTime> dateTime = default!;
diff --git a/samples/client/petstore/csharp/generichost/net10/SourceGeneration/src/Org.OpenAPITools.Test/Api/PetApiTests.cs b/samples/client/petstore/csharp/generichost/net10/SourceGeneration/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
index 49e7b21b53c2..6bb1f953987c 100644
--- a/samples/client/petstore/csharp/generichost/net10/SourceGeneration/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/net10/SourceGeneration/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
@@ -137,7 +137,7 @@ public async Task UploadFileAsyncTest()
         {
             long petId = default!;
             Client.Option<string> additionalMetadata = default!;
-            Client.Option<System.IO.Stream> file = default!;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> file = default!;
             var response = await _instance.UploadFileAsync(petId, additionalMetadata, file);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
@@ -150,11 +150,24 @@ public async Task UploadFileAsyncTest()
         public async Task UploadFileWithRequiredFileAsyncTest()
         {
             long petId = default!;
-            System.IO.Stream requiredFile = default!;
+            Org.OpenAPITools.Client.FileParameter requiredFile = default!;
             Client.Option<string> additionalMetadata = default!;
             var response = await _instance.UploadFileWithRequiredFileAsync(petId, requiredFile, additionalMetadata);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
         }
+
+        /// <summary>
+        /// Test UploadFiles
+        /// </summary>
+        [Fact (Skip = "not implemented")]
+        public async Task UploadFilesAsyncTest()
+        {
+            List<Org.OpenAPITools.Client.FileParameter> files = default!;
+            long petId = default!;
+            var response = await _instance.UploadFilesAsync(files, petId);
+            var model = response.Ok();
+            Assert.IsType<ApiResponse>(model);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/net10/SourceGeneration/src/Org.OpenAPITools/Api/DefaultApi.cs b/samples/client/petstore/csharp/generichost/net10/SourceGeneration/src/Org.OpenAPITools/Api/DefaultApi.cs
index 2391c7e1ee03..46b798fe32ca 100644
--- a/samples/client/petstore/csharp/generichost/net10/SourceGeneration/src/Org.OpenAPITools/Api/DefaultApi.cs
+++ b/samples/client/petstore/csharp/generichost/net10/SourceGeneration/src/Org.OpenAPITools/Api/DefaultApi.cs
@@ -766,15 +766,12 @@ public async Task<IGetCountryApiResponse> GetCountryAsync(string country, System
                         ? "/country"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/country");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("country", ClientUtils.ParameterToString(country)));
 
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
-
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("country", ClientUtils.ParameterToString(country)));
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
 
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -782,11 +779,6 @@ public async Task<IGetCountryApiResponse> GetCountryAsync(string country, System
                         "application/x-www-form-urlencoded"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/net10/SourceGeneration/src/Org.OpenAPITools/Api/FakeApi.cs b/samples/client/petstore/csharp/generichost/net10/SourceGeneration/src/Org.OpenAPITools/Api/FakeApi.cs
index 262a94ef2520..54a1c8c85360 100644
--- a/samples/client/petstore/csharp/generichost/net10/SourceGeneration/src/Org.OpenAPITools/Api/FakeApi.cs
+++ b/samples/client/petstore/csharp/generichost/net10/SourceGeneration/src/Org.OpenAPITools/Api/FakeApi.cs
@@ -332,7 +332,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -356,7 +356,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>?&gt;</returns>
-        Task<ITestEndpointParametersApiResponse?> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse?> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// To test enum parameters
@@ -4082,7 +4082,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<System.IO.Stream> binary, ref Option<string> callback, ref Option<DateOnly> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
+        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<Org.OpenAPITools.Client.FileParameter> binary, ref Option<string> callback, ref Option<DateOnly> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
 
         /// <summary>
         /// Validates the request parameters
@@ -4094,7 +4094,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="password"></param>
         /// <param name="varString"></param>
         /// <returns></returns>
-        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<System.IO.Stream> binary, Option<string> callback, Option<string> password, Option<string> varString)
+        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<string> password, Option<string> varString)
         {
             if (patternWithoutDelimiter == null)
                 throw new ArgumentNullException(nameof(patternWithoutDelimiter));
@@ -4133,7 +4133,7 @@ private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLog = false;
             AfterTestEndpointParameters(ref suppressDefaultLog, apiResponseLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4160,7 +4160,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -4182,7 +4182,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorTestEndpointParameters(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4211,7 +4211,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트  Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -4232,7 +4232,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse?> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse?> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -4264,7 +4264,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -4283,51 +4283,48 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         ? "/fake"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("number", ClientUtils.ParameterToString(number)));
 
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("pattern_without_delimiter", ClientUtils.ParameterToString(patternWithoutDelimiter)));
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("byte", ClientUtils.ParameterToString(varByte)));
 
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("number", ClientUtils.ParameterToString(number)));
-
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("pattern_without_delimiter", ClientUtils.ParameterToString(patternWithoutDelimiter)));
-
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("byte", ClientUtils.ParameterToString(varByte)));
-
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("double", ClientUtils.ParameterToString(varDouble)));
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("double", ClientUtils.ParameterToString(varDouble)));
 
                     if (binary.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(binary.Value));
+                        throw new NotSupportedException("File parameters cannot be sent with application/x-www-form-urlencoded. Change the operation's content type to multipart/form-data.");
 
                     if (callback.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("callback", ClientUtils.ParameterToString(callback.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("callback", ClientUtils.ParameterToString(callback.Value)));
 
                     if (date.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("date", ClientUtils.ParameterToString(date.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("date", ClientUtils.ParameterToString(date.Value)));
 
                     if (dateTime.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("dateTime", ClientUtils.ParameterToString(dateTime.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("dateTime", ClientUtils.ParameterToString(dateTime.Value)));
 
                     if (int32.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("int32", ClientUtils.ParameterToString(int32.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("int32", ClientUtils.ParameterToString(int32.Value)));
 
                     if (int64.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("int64", ClientUtils.ParameterToString(int64.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("int64", ClientUtils.ParameterToString(int64.Value)));
 
                     if (integer.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("integer", ClientUtils.ParameterToString(integer.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("integer", ClientUtils.ParameterToString(integer.Value)));
 
                     if (password.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("password", ClientUtils.ParameterToString(password.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("password", ClientUtils.ParameterToString(password.Value)));
 
                     if (varFloat.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("float", ClientUtils.ParameterToString(varFloat.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("float", ClientUtils.ParameterToString(varFloat.Value)));
 
                     if (varString.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("string", ClientUtils.ParameterToString(varString.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("string", ClientUtils.ParameterToString(varString.Value)));
+
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -4342,11 +4339,6 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         "application/x-www-form-urlencoded"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -4639,17 +4631,16 @@ public async Task<ITestEnumParametersApiResponse> TestEnumParametersAsync(Option
                     if (enumHeaderStringArray.IsSet)
                         httpRequestMessageLocalVar.Headers.Add("enum_header_string_array", ClientUtils.ParameterToString(enumHeaderStringArray.Value));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
-
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (enumFormString.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("enum_form_string", ClientUtils.ParameterToString(enumFormString.Value)));
+                    if (enumFormString.IsSet)
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("enum_form_string", ClientUtils.ParameterToString(enumFormString.Value)));
 
                     if (enumFormStringArray.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("enum_form_string_array", ClientUtils.ParameterToString(enumFormStringArray.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("enum_form_string_array", ClientUtils.ParameterToString(enumFormStringArray.Value)));
+
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
 
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -4657,11 +4648,6 @@ public async Task<ITestEnumParametersApiResponse> TestEnumParametersAsync(Option
                         "application/x-www-form-urlencoded"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Get;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -5548,17 +5534,14 @@ public async Task<ITestJsonFormDataApiResponse> TestJsonFormDataAsync(string par
                         ? "/fake/jsonFormData"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/jsonFormData");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("param", ClientUtils.ParameterToString(param)));
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("param2", ClientUtils.ParameterToString(param2)));
 
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("param", ClientUtils.ParameterToString(param)));
-
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("param2", ClientUtils.ParameterToString(param2)));
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
 
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -5566,11 +5549,6 @@ public async Task<ITestJsonFormDataApiResponse> TestJsonFormDataAsync(string par
                         "application/x-www-form-urlencoded"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Get;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/net10/SourceGeneration/src/Org.OpenAPITools/Api/PetApi.cs b/samples/client/petstore/csharp/generichost/net10/SourceGeneration/src/Org.OpenAPITools/Api/PetApi.cs
index 2d7e4dab0b84..c5de9cd55ad1 100644
--- a/samples/client/petstore/csharp/generichost/net10/SourceGeneration/src/Org.OpenAPITools/Api/PetApi.cs
+++ b/samples/client/petstore/csharp/generichost/net10/SourceGeneration/src/Org.OpenAPITools/Api/PetApi.cs
@@ -218,7 +218,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image
@@ -231,7 +231,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>?&gt;</returns>
-        Task<IUploadFileApiResponse?> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse?> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -245,7 +245,7 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -258,7 +258,32 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>?&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse?> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse?> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>?&gt;</returns>
+        Task<IUploadFilesApiResponse?> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
     }
 
     /// <summary>
@@ -417,6 +442,18 @@ public interface IUploadFileWithRequiredFileApiResponse : Org.OpenAPITools.Clien
         bool IsOk { get; }
     }
 
+    /// <summary>
+    /// The <see cref="IUploadFilesApiResponse"/>
+    /// </summary>
+    public interface IUploadFilesApiResponse : Org.OpenAPITools.Client.IApiResponse, IOk<Org.OpenAPITools.Model.ApiResponse?>
+    {
+        /// <summary>
+        /// Returns true if the response is 200 Ok
+        /// </summary>
+        /// <returns></returns>
+        bool IsOk { get; }
+    }
+
     /// <summary>
     /// Represents a collection of functions to interact with the API endpoints
     /// </summary>
@@ -601,6 +638,26 @@ internal void ExecuteOnErrorUploadFileWithRequiredFile(Exception exception)
         {
             OnErrorUploadFileWithRequiredFile?.Invoke(this, new ExceptionEventArgs(exception));
         }
+
+        /// <summary>
+        /// The event raised after the server response
+        /// </summary>
+        public event EventHandler<ApiResponseEventArgs>? OnUploadFiles;
+
+        /// <summary>
+        /// The event raised after an error querying the server
+        /// </summary>
+        public event EventHandler<ExceptionEventArgs>? OnErrorUploadFiles;
+
+        internal void ExecuteOnUploadFiles(PetApi.UploadFilesApiResponse apiResponse)
+        {
+            OnUploadFiles?.Invoke(this, new ApiResponseEventArgs(apiResponse));
+        }
+
+        internal void ExecuteOnErrorUploadFiles(Exception exception)
+        {
+            OnErrorUploadFiles?.Invoke(this, new ExceptionEventArgs(exception));
+        }
     }
 
     /// <summary>
@@ -2332,17 +2389,16 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (name.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("name", ClientUtils.ParameterToString(name.Value)));
+                    if (name.IsSet)
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("name", ClientUtils.ParameterToString(name.Value)));
 
                     if (status.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("status", ClientUtils.ParameterToString(status.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("status", ClientUtils.ParameterToString(status.Value)));
+
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -2357,11 +2413,6 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         "application/x-www-form-urlencoded"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -2461,7 +2512,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<System.IO.Stream> file);
+        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Validates the request parameters
@@ -2469,7 +2520,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
         /// <returns></returns>
-        private void ValidateUploadFile(Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void ValidateUploadFile(Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             if (additionalMetadata.IsSet && additionalMetadata.Value == null)
                 throw new ArgumentNullException(nameof(additionalMetadata));
@@ -2485,7 +2536,7 @@ private void ValidateUploadFile(Option<string> additionalMetadata, Option<System
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLog = false;
             AfterUploadFile(ref suppressDefaultLog, apiResponseLocalVar, petId, additionalMetadata, file);
@@ -2501,7 +2552,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2512,7 +2563,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, additionalMetadata, file);
@@ -2530,7 +2581,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// uploads an image 
@@ -2540,7 +2591,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse?> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse?> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2561,7 +2612,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2581,17 +2632,23 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImage");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (additionalMetadata.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
+                    if (additionalMetadata.IsSet)
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
 
                     if (file.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(file.Value));
+                    {
+                        var streamContentLocalVar = new StreamContent(file.Value.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "file", file.Value.FileName ?? "file");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -2606,11 +2663,6 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         "multipart/form-data"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json"
                     };
@@ -2751,7 +2803,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFileWithRequiredFile(ref long petId, ref System.IO.Stream requiredFile, ref Option<string> additionalMetadata);
+        partial void FormatUploadFileWithRequiredFile(ref long petId, ref Org.OpenAPITools.Client.FileParameter requiredFile, ref Option<string> additionalMetadata);
 
         /// <summary>
         /// Validates the request parameters
@@ -2759,7 +2811,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
         /// <returns></returns>
-        private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void ValidateUploadFileWithRequiredFile(Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             if (requiredFile == null)
                 throw new ArgumentNullException(nameof(requiredFile));
@@ -2775,7 +2827,7 @@ private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, O
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLog = false;
             AfterUploadFileWithRequiredFile(ref suppressDefaultLog, apiResponseLocalVar, petId, requiredFile, additionalMetadata);
@@ -2791,7 +2843,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2802,7 +2854,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFileWithRequiredFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, requiredFile, additionalMetadata);
@@ -2820,7 +2872,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// uploads an image (required) 
@@ -2830,7 +2882,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse?> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse?> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2851,7 +2903,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2871,16 +2923,22 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/{petId}/uploadImageWithRequiredFile");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    multipartContentLocalVar.Add(new StreamContent(requiredFile));
+                    {
+                        var streamContentLocalVar = new StreamContent(requiredFile.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "requiredFile", requiredFile.FileName ?? "requiredFile");
+                    }
 
                     if (additionalMetadata.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -2895,11 +2953,6 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         "multipart/form-data"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json",
                         "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
@@ -3040,5 +3093,283 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
 
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
+
+        partial void FormatUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files, ref long petId);
+
+        /// <summary>
+        /// Validates the request parameters
+        /// </summary>
+        /// <param name="files"></param>
+        /// <returns></returns>
+        private void ValidateUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files)
+        {
+            if (files == null)
+                throw new ArgumentNullException(nameof(files));
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void AfterUploadFilesDefaultImplementation(IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLog = false;
+            AfterUploadFiles(ref suppressDefaultLog, apiResponseLocalVar, files, petId);
+            if (!suppressDefaultLog)
+                Logger.LogInformation("{0,-9} | {1} | {2}", (apiResponseLocalVar.DownloadedAt - apiResponseLocalVar.RequestedAt).TotalSeconds, apiResponseLocalVar.StatusCode, apiResponseLocalVar.Path);
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="suppressDefaultLog"></param>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void AfterUploadFiles(ref bool suppressDefaultLog, IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// Logs exceptions that occur while retrieving the server response
+        /// </summary>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void OnErrorUploadFilesDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLogLocalVar = false;
+            OnErrorUploadFiles(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, files, petId);
+            if (!suppressDefaultLogLocalVar)
+                Logger.LogError(exceptionLocalVar, "An error occurred while sending the request to the server.");
+        }
+
+        /// <summary>
+        /// A partial method that gives developers a way to provide customized exception handling
+        /// </summary>
+        /// <param name="suppressDefaultLogLocalVar"></param>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void OnErrorUploadFiles(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse?> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            try
+            {
+                return await UploadFilesAsync(files, petId, cancellationToken).ConfigureAwait(false);
+            }
+            catch (Exception)
+            {
+                return null;
+            }
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            UriBuilder uriBuilderLocalVar = new UriBuilder();
+
+            try
+            {
+                ValidateUploadFiles(files);
+
+                FormatUploadFiles(files, ref petId);
+
+                using (HttpRequestMessage httpRequestMessageLocalVar = new HttpRequestMessage())
+                {
+                    uriBuilderLocalVar.Host = HttpClient.BaseAddress!.Host;
+                    uriBuilderLocalVar.Port = HttpClient.BaseAddress.Port;
+                    uriBuilderLocalVar.Scheme = HttpClient.BaseAddress.Scheme;
+                    uriBuilderLocalVar.Path = HttpClient.BaseAddress.AbsolutePath == "/"
+                        ? "/pet/{petId}/uploadImages"
+                        : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImages");
+                    uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
+
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
+
+                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
+
+                    foreach (Org.OpenAPITools.Client.FileParameter fileParameterLocalVar in files)
+                    {
+                        var streamContentLocalVar = new StreamContent(fileParameterLocalVar.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "files", fileParameterLocalVar.FileName ?? "files");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
+
+                    List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
+                    httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
+
+                    OAuthToken oauthTokenLocalVar1 = (OAuthToken) await OauthTokenProvider.GetAsync(cancellation: cancellationToken).ConfigureAwait(false);
+
+                    tokenBaseLocalVars.Add(oauthTokenLocalVar1);
+
+                    oauthTokenLocalVar1.UseInHeader(httpRequestMessageLocalVar, "");
+
+                    string[] contentTypes = new string[] {
+                        "multipart/form-data"
+                    };
+
+                    string[] acceptLocalVars = new string[] {
+                        "application/json"
+                    };
+
+                    IEnumerable<MediaTypeWithQualityHeaderValue> acceptHeaderValuesLocalVar = ClientUtils.SelectHeaderAcceptArray(acceptLocalVars);
+
+                    foreach (var acceptLocalVar in acceptHeaderValuesLocalVar)
+                        httpRequestMessageLocalVar.Headers.Accept.Add(acceptLocalVar);
+
+                    httpRequestMessageLocalVar.Method = HttpMethod.Post;
+
+                    DateTime requestedAtLocalVar = DateTime.UtcNow;
+
+                    using (HttpResponseMessage httpResponseMessageLocalVar = await HttpClient.SendAsync(httpRequestMessageLocalVar, cancellationToken).ConfigureAwait(false))
+                    {
+                        ILogger<UploadFilesApiResponse> apiResponseLoggerLocalVar = LoggerFactory.CreateLogger<UploadFilesApiResponse>();
+                        UploadFilesApiResponse apiResponseLocalVar;
+
+                        switch ((int)httpResponseMessageLocalVar.StatusCode) {
+                            default: {
+                                string responseContentLocalVar = await httpResponseMessageLocalVar.Content.ReadAsStringAsync(cancellationToken).ConfigureAwait(false);
+                                apiResponseLocalVar = new(apiResponseLoggerLocalVar, httpRequestMessageLocalVar, httpResponseMessageLocalVar, responseContentLocalVar, "/pet/{petId}/uploadImages", requestedAtLocalVar, _jsonSerializerOptions);
+
+                                break;
+                            }
+                        }
+
+                        AfterUploadFilesDefaultImplementation(apiResponseLocalVar, files, petId);
+
+                        Events.ExecuteOnUploadFiles(apiResponseLocalVar);
+
+                        if (apiResponseLocalVar.StatusCode == (HttpStatusCode) 429)
+                            foreach(TokenBase tokenBaseLocalVar in tokenBaseLocalVars)
+                                tokenBaseLocalVar.BeginRateLimit();
+
+                        return apiResponseLocalVar;
+                    }
+                }
+            }
+            catch(Exception e)
+            {
+                OnErrorUploadFilesDefaultImplementation(e, "/pet/{petId}/uploadImages", uriBuilderLocalVar.Path, files, petId);
+                Events.ExecuteOnErrorUploadFiles(e);
+                throw;
+            }
+        }
+
+        /// <summary>
+        /// The <see cref="UploadFilesApiResponse"/>
+        /// </summary>
+        public partial class UploadFilesApiResponse : Org.OpenAPITools.Client.ApiResponse, IUploadFilesApiResponse
+        {
+            /// <summary>
+            /// The logger
+            /// </summary>
+            public ILogger<UploadFilesApiResponse> Logger { get; }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="rawContent"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, string rawContent, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, rawContent, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="contentStream"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, System.IO.Stream contentStream, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, contentStream, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            partial void OnCreated(global::System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage);
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public bool IsOk => 200 == (int)StatusCode;
+
+            /// <summary>
+            /// Deserializes the response if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public Org.OpenAPITools.Model.ApiResponse? Ok()
+            {
+                // This logic may be modified with the AsModel.mustache template
+                return IsOk
+                    ? System.Text.Json.JsonSerializer.Deserialize<Org.OpenAPITools.Model.ApiResponse>(RawContent, _jsonSerializerOptions)
+                    : null;
+            }
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok and the deserialized response is not null
+            /// </summary>
+            /// <param name="result"></param>
+            /// <returns></returns>
+            public bool TryOk([NotNullWhen(true)]out Org.OpenAPITools.Model.ApiResponse? result)
+            {
+                result = null;
+
+                try
+                {
+                    result = Ok();
+                } catch (Exception e)
+                {
+                    OnDeserializationErrorDefaultImplementation(e, (HttpStatusCode)200);
+                }
+
+                return result != null;
+            }
+
+            private void OnDeserializationErrorDefaultImplementation(Exception exception, HttpStatusCode httpStatusCode)
+            {
+                bool suppressDefaultLog = false;
+                OnDeserializationError(ref suppressDefaultLog, exception, httpStatusCode);
+                if (!suppressDefaultLog)
+                    Logger.LogError(exception, "An error occurred while deserializing the {code} response.", httpStatusCode);
+            }
+
+            partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/net10/SourceGeneration/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net10/SourceGeneration/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..77779fe7d75a
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net10/SourceGeneration/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,42 @@
+// <auto-generated>
+/*
+ * OpenAPI Petstore
+ *
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+#nullable enable
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string? FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string? fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net10/UseDateTimeForDate/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net10/UseDateTimeForDate/.openapi-generator/FILES
index 5abbcf46f35c..e28da391730f 100644
--- a/samples/client/petstore/csharp/generichost/net10/UseDateTimeForDate/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net10/UseDateTimeForDate/.openapi-generator/FILES
@@ -21,6 +21,7 @@ src/Org.OpenAPITools/Client/CookieContainer.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/JsonSerializerOptionsProvider.cs
 src/Org.OpenAPITools/Client/Option.cs
diff --git a/samples/client/petstore/csharp/generichost/net10/UseDateTimeForDate/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net10/UseDateTimeForDate/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..11da1d925144
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net10/UseDateTimeForDate/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,42 @@
+// <auto-generated>
+/*
+ * OpenAPI Dates
+ *
+ * Thic spec contains endpoints with dates in different formats
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+#nullable enable
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string? FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string? fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net4.7/AllOf/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net4.7/AllOf/.openapi-generator/FILES
index 47b2b9b5c4f4..1c80f1449c66 100644
--- a/samples/client/petstore/csharp/generichost/net4.7/AllOf/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net4.7/AllOf/.openapi-generator/FILES
@@ -23,6 +23,7 @@ src/Org.OpenAPITools/Client/CookieContainer.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/JsonSerializerOptionsProvider.cs
 src/Org.OpenAPITools/Client/Option.cs
diff --git a/samples/client/petstore/csharp/generichost/net4.7/AllOf/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net4.7/AllOf/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..936f8415fda6
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net4.7/AllOf/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,40 @@
+// <auto-generated>
+/*
+ * Example
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net4.7/AnyOf/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net4.7/AnyOf/.openapi-generator/FILES
index 59cc1ea25a08..5e82fcb80ae5 100644
--- a/samples/client/petstore/csharp/generichost/net4.7/AnyOf/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net4.7/AnyOf/.openapi-generator/FILES
@@ -23,6 +23,7 @@ src/Org.OpenAPITools/Client/CookieContainer.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/JsonSerializerOptionsProvider.cs
 src/Org.OpenAPITools/Client/Option.cs
diff --git a/samples/client/petstore/csharp/generichost/net4.7/AnyOf/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net4.7/AnyOf/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..5c8e0767f76a
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net4.7/AnyOf/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,40 @@
+// <auto-generated>
+/*
+ * fruity
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * The version of the OpenAPI document: 0.0.1
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net4.7/AnyOfNoCompare/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net4.7/AnyOfNoCompare/.openapi-generator/FILES
index 59cc1ea25a08..5e82fcb80ae5 100644
--- a/samples/client/petstore/csharp/generichost/net4.7/AnyOfNoCompare/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net4.7/AnyOfNoCompare/.openapi-generator/FILES
@@ -23,6 +23,7 @@ src/Org.OpenAPITools/Client/CookieContainer.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/JsonSerializerOptionsProvider.cs
 src/Org.OpenAPITools/Client/Option.cs
diff --git a/samples/client/petstore/csharp/generichost/net4.7/AnyOfNoCompare/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net4.7/AnyOfNoCompare/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..5c8e0767f76a
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net4.7/AnyOfNoCompare/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,40 @@
+// <auto-generated>
+/*
+ * fruity
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * The version of the OpenAPI document: 0.0.1
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net4.7/FormModels/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net4.7/FormModels/.openapi-generator/FILES
index 3c592107ec19..4d9b3d8248d3 100644
--- a/samples/client/petstore/csharp/generichost/net4.7/FormModels/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net4.7/FormModels/.openapi-generator/FILES
@@ -163,6 +163,7 @@ src/Org.OpenAPITools/Client/CookieContainer.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningToken.cs
diff --git a/samples/client/petstore/csharp/generichost/net4.7/FormModels/api/openapi.yaml b/samples/client/petstore/csharp/generichost/net4.7/FormModels/api/openapi.yaml
index a9ab8dd51c13..7017affc0b9c 100644
--- a/samples/client/petstore/csharp/generichost/net4.7/FormModels/api/openapi.yaml
+++ b/samples/client/petstore/csharp/generichost/net4.7/FormModels/api/openapi.yaml
@@ -326,6 +326,40 @@ paths:
       summary: uploads an image
       tags:
       - pet
+  /pet/{petId}/uploadImages:
+    post:
+      description: ""
+      operationId: uploadFiles
+      parameters:
+      - description: ID of pet to update
+        explode: false
+        in: path
+        name: petId
+        required: true
+        schema:
+          format: int64
+          type: integer
+        style: simple
+      requestBody:
+        content:
+          multipart/form-data:
+            schema:
+              $ref: "#/components/schemas/uploadFiles_request"
+        required: true
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ApiResponse"
+          description: successful operation
+      security:
+      - petstore_auth:
+        - write:pets
+        - read:pets
+      summary: uploads an images
+      tags:
+      - pet
   /store/inventory:
     get:
       description: Returns a map of status codes to quantities
@@ -2748,6 +2782,16 @@ components:
           format: binary
           type: string
       type: object
+    uploadFiles_request:
+      properties:
+        files:
+          items:
+            format: binary
+            type: string
+          type: array
+      required:
+      - files
+      type: object
     testEnumParameters_request_enum_form_string_array_inner:
       default: $
       enum:
diff --git a/samples/client/petstore/csharp/generichost/net4.7/FormModels/docs/apis/PetApi.md b/samples/client/petstore/csharp/generichost/net4.7/FormModels/docs/apis/PetApi.md
index e32c1e31e089..59d4ef8e6df0 100644
--- a/samples/client/petstore/csharp/generichost/net4.7/FormModels/docs/apis/PetApi.md
+++ b/samples/client/petstore/csharp/generichost/net4.7/FormModels/docs/apis/PetApi.md
@@ -13,6 +13,7 @@ All URIs are relative to *http://petstore.swagger.io:80/v2*
 | [**UpdatePetWithForm**](PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data |
 | [**UploadFile**](PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image |
 | [**UploadFileWithRequiredFile**](PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required) |
+| [**UploadFiles**](PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images |
 
 <a id="addpet"></a>
 # **AddPet**
@@ -341,3 +342,38 @@ uploads an image (required)
 
 [[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
 
+<a id="uploadfiles"></a>
+# **UploadFiles**
+> ApiResponse UploadFiles (List<System.IO.Stream> files, long petId)
+
+uploads an images
+
+
+### Parameters
+
+| Name | Type | Description | Notes |
+|------|------|-------------|-------|
+| **files** | **List&lt;System.IO.Stream&gt;** |  |  |
+| **petId** | **long** | ID of pet to update |  |
+
+### Return type
+
+[**ApiResponse**](ApiResponse.md)
+
+### Authorization
+
+[petstore_auth](../README.md#petstore_auth)
+
+### HTTP request headers
+
+ - **Content-Type**: multipart/form-data
+ - **Accept**: application/json
+
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **200** | successful operation |  -  |
+
+[[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
+
diff --git a/samples/client/petstore/csharp/generichost/net4.7/FormModels/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs b/samples/client/petstore/csharp/generichost/net4.7/FormModels/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
index dbca7881df47..62c158ea45da 100644
--- a/samples/client/petstore/csharp/generichost/net4.7/FormModels/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/net4.7/FormModels/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
@@ -196,7 +196,7 @@ public async Task TestEndpointParametersAsyncTest()
             string patternWithoutDelimiter = default;
             byte[] varByte = default;
             double varDouble = default;
-            Client.Option<System.IO.Stream> binary = default;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> binary = default;
             Client.Option<string> callback = default;
             Client.Option<DateTime> date = default;
             Client.Option<DateTime> dateTime = default;
diff --git a/samples/client/petstore/csharp/generichost/net4.7/FormModels/src/Org.OpenAPITools.Test/Api/PetApiTests.cs b/samples/client/petstore/csharp/generichost/net4.7/FormModels/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
index 1f1d7f6c4576..a4aa8f3e245d 100644
--- a/samples/client/petstore/csharp/generichost/net4.7/FormModels/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/net4.7/FormModels/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
@@ -137,7 +137,7 @@ public async Task UploadFileAsyncTest()
         {
             long petId = default;
             Client.Option<string> additionalMetadata = default;
-            Client.Option<System.IO.Stream> file = default;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> file = default;
             var response = await _instance.UploadFileAsync(petId, additionalMetadata, file);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
@@ -150,11 +150,24 @@ public async Task UploadFileAsyncTest()
         public async Task UploadFileWithRequiredFileAsyncTest()
         {
             long petId = default;
-            System.IO.Stream requiredFile = default;
+            Org.OpenAPITools.Client.FileParameter requiredFile = default;
             Client.Option<string> additionalMetadata = default;
             var response = await _instance.UploadFileWithRequiredFileAsync(petId, requiredFile, additionalMetadata);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
         }
+
+        /// <summary>
+        /// Test UploadFiles
+        /// </summary>
+        [Fact (Skip = "not implemented")]
+        public async Task UploadFilesAsyncTest()
+        {
+            List<Org.OpenAPITools.Client.FileParameter> files = default;
+            long petId = default;
+            var response = await _instance.UploadFilesAsync(files, petId);
+            var model = response.Ok();
+            Assert.IsType<ApiResponse>(model);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/net4.7/FormModels/src/Org.OpenAPITools/Api/DefaultApi.cs b/samples/client/petstore/csharp/generichost/net4.7/FormModels/src/Org.OpenAPITools/Api/DefaultApi.cs
index 1bbf43279f7c..24a69b84527e 100644
--- a/samples/client/petstore/csharp/generichost/net4.7/FormModels/src/Org.OpenAPITools/Api/DefaultApi.cs
+++ b/samples/client/petstore/csharp/generichost/net4.7/FormModels/src/Org.OpenAPITools/Api/DefaultApi.cs
@@ -763,27 +763,19 @@ public async Task<IGetCountryApiResponse> GetCountryAsync(string country, System
                         ? "/country"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/country");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("country", ClientUtils.ParameterToString(country)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = new HttpMethod("POST");
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/net4.7/FormModels/src/Org.OpenAPITools/Api/FakeApi.cs b/samples/client/petstore/csharp/generichost/net4.7/FormModels/src/Org.OpenAPITools/Api/FakeApi.cs
index ed9c440bd2b8..9f2605d1777f 100644
--- a/samples/client/petstore/csharp/generichost/net4.7/FormModels/src/Org.OpenAPITools/Api/FakeApi.cs
+++ b/samples/client/petstore/csharp/generichost/net4.7/FormModels/src/Org.OpenAPITools/Api/FakeApi.cs
@@ -330,7 +330,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -354,7 +354,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// To test enum parameters
@@ -4071,7 +4071,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<System.IO.Stream> binary, ref Option<string> callback, ref Option<DateTime> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
+        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<Org.OpenAPITools.Client.FileParameter> binary, ref Option<string> callback, ref Option<DateTime> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
 
         /// <summary>
         /// Validates the request parameters
@@ -4083,7 +4083,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="password"></param>
         /// <param name="varString"></param>
         /// <returns></returns>
-        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<System.IO.Stream> binary, Option<string> callback, Option<string> password, Option<string> varString)
+        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<string> password, Option<string> varString)
         {
             if (patternWithoutDelimiter == null)
                 throw new ArgumentNullException(nameof(patternWithoutDelimiter));
@@ -4122,7 +4122,7 @@ private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLog = false;
             AfterTestEndpointParameters(ref suppressDefaultLog, apiResponseLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4149,7 +4149,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -4171,7 +4171,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorTestEndpointParameters(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4200,7 +4200,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트  Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -4221,7 +4221,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -4253,7 +4253,7 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDe
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -4272,14 +4272,8 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         ? "/fake"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("number", ClientUtils.ParameterToString(number)));
 
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("pattern_without_delimiter", ClientUtils.ParameterToString(patternWithoutDelimiter)));
@@ -4289,7 +4283,7 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("double", ClientUtils.ParameterToString(varDouble)));
 
                     if (binary.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(binary.Value));
+                        throw new NotSupportedException("File parameters cannot be sent with application/x-www-form-urlencoded. Change the operation's content type to multipart/form-data.");
 
                     if (callback.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("callback", ClientUtils.ParameterToString(callback.Value)));
@@ -4318,6 +4312,9 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                     if (varString.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("string", ClientUtils.ParameterToString(varString.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -4331,11 +4328,6 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = new HttpMethod("POST");
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -4616,29 +4608,23 @@ public async Task<ITestEnumParametersApiResponse> TestEnumParametersAsync(Option
                     if (enumHeaderStringArray.IsSet)
                         httpRequestMessageLocalVar.Headers.Add("enum_header_string_array", ClientUtils.ParameterToString(enumHeaderStringArray.Value));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (enumFormString.IsSet)
+                    if (enumFormString.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("enum_form_string", ClientUtils.ParameterToString(enumFormString.Value)));
 
                     if (enumFormStringArray.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("enum_form_string_array", ClientUtils.ParameterToString(enumFormStringArray.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = new HttpMethod("GET");
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -5524,29 +5510,21 @@ public async Task<ITestJsonFormDataApiResponse> TestJsonFormDataAsync(string par
                         ? "/fake/jsonFormData"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/jsonFormData");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("param", ClientUtils.ParameterToString(param)));
 
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("param2", ClientUtils.ParameterToString(param2)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = new HttpMethod("GET");
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/net4.7/FormModels/src/Org.OpenAPITools/Api/PetApi.cs b/samples/client/petstore/csharp/generichost/net4.7/FormModels/src/Org.OpenAPITools/Api/PetApi.cs
index 0eaf83e1f41e..11f4b994064c 100644
--- a/samples/client/petstore/csharp/generichost/net4.7/FormModels/src/Org.OpenAPITools/Api/PetApi.cs
+++ b/samples/client/petstore/csharp/generichost/net4.7/FormModels/src/Org.OpenAPITools/Api/PetApi.cs
@@ -216,7 +216,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image
@@ -229,7 +229,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -243,7 +243,7 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -256,7 +256,32 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        Task<IUploadFilesApiResponse> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
     }
 
     /// <summary>
@@ -415,6 +440,18 @@ public interface IUploadFileWithRequiredFileApiResponse : Org.OpenAPITools.Clien
         bool IsOk { get; }
     }
 
+    /// <summary>
+    /// The <see cref="IUploadFilesApiResponse"/>
+    /// </summary>
+    public interface IUploadFilesApiResponse : Org.OpenAPITools.Client.IApiResponse, IOk<Org.OpenAPITools.Model.ApiResponse>
+    {
+        /// <summary>
+        /// Returns true if the response is 200 Ok
+        /// </summary>
+        /// <returns></returns>
+        bool IsOk { get; }
+    }
+
     /// <summary>
     /// Represents a collection of functions to interact with the API endpoints
     /// </summary>
@@ -599,6 +636,26 @@ internal void ExecuteOnErrorUploadFileWithRequiredFile(Exception exception)
         {
             OnErrorUploadFileWithRequiredFile?.Invoke(this, new ExceptionEventArgs(exception));
         }
+
+        /// <summary>
+        /// The event raised after the server response
+        /// </summary>
+        public event EventHandler<ApiResponseEventArgs> OnUploadFiles;
+
+        /// <summary>
+        /// The event raised after an error querying the server
+        /// </summary>
+        public event EventHandler<ExceptionEventArgs> OnErrorUploadFiles;
+
+        internal void ExecuteOnUploadFiles(PetApi.UploadFilesApiResponse apiResponse)
+        {
+            OnUploadFiles?.Invoke(this, new ApiResponseEventArgs(apiResponse));
+        }
+
+        internal void ExecuteOnErrorUploadFiles(Exception exception)
+        {
+            OnErrorUploadFiles?.Invoke(this, new ExceptionEventArgs(exception));
+        }
     }
 
     /// <summary>
@@ -2326,18 +2383,17 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (name.IsSet)
+                    if (name.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("name", ClientUtils.ParameterToString(name.Value)));
 
                     if (status.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("status", ClientUtils.ParameterToString(status.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -2351,11 +2407,6 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = new HttpMethod("POST");
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -2455,7 +2506,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<System.IO.Stream> file);
+        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Validates the request parameters
@@ -2463,7 +2514,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
         /// <returns></returns>
-        private void ValidateUploadFile(Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void ValidateUploadFile(Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             if (additionalMetadata.IsSet && additionalMetadata.Value == null)
                 throw new ArgumentNullException(nameof(additionalMetadata));
@@ -2479,7 +2530,7 @@ private void ValidateUploadFile(Option<string> additionalMetadata, Option<System
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLog = false;
             AfterUploadFile(ref suppressDefaultLog, apiResponseLocalVar, petId, additionalMetadata, file);
@@ -2495,7 +2546,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2506,7 +2557,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, additionalMetadata, file);
@@ -2524,7 +2575,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// uploads an image 
@@ -2534,7 +2585,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2555,7 +2606,7 @@ public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, O
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2575,17 +2626,23 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImage");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (additionalMetadata.IsSet)
+                    if (additionalMetadata.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
 
                     if (file.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(file.Value));
+                    {
+                        var streamContentLocalVar = new StreamContent(file.Value.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "file", file.Value.FileName ?? "file");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -2600,11 +2657,6 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         "multipart/form-data"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json"
                     };
@@ -2744,7 +2796,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFileWithRequiredFile(ref long petId, ref System.IO.Stream requiredFile, ref Option<string> additionalMetadata);
+        partial void FormatUploadFileWithRequiredFile(ref long petId, ref Org.OpenAPITools.Client.FileParameter requiredFile, ref Option<string> additionalMetadata);
 
         /// <summary>
         /// Validates the request parameters
@@ -2752,7 +2804,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
         /// <returns></returns>
-        private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void ValidateUploadFileWithRequiredFile(Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             if (requiredFile == null)
                 throw new ArgumentNullException(nameof(requiredFile));
@@ -2768,7 +2820,7 @@ private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, O
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLog = false;
             AfterUploadFileWithRequiredFile(ref suppressDefaultLog, apiResponseLocalVar, petId, requiredFile, additionalMetadata);
@@ -2784,7 +2836,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2795,7 +2847,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFileWithRequiredFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, requiredFile, additionalMetadata);
@@ -2813,7 +2865,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// uploads an image (required) 
@@ -2823,7 +2875,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2844,7 +2896,7 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2864,17 +2916,23 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/{petId}/uploadImageWithRequiredFile");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    multipartContentLocalVar.Add(new StreamContent(requiredFile));
+                    {
+                        var streamContentLocalVar = new StreamContent(requiredFile.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "requiredFile", requiredFile.FileName ?? "requiredFile");
+                    }
 
                     if (additionalMetadata.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
 
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -2888,11 +2946,6 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         "multipart/form-data"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json",
                         "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
@@ -3032,5 +3085,282 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
 
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
+
+        partial void FormatUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files, ref long petId);
+
+        /// <summary>
+        /// Validates the request parameters
+        /// </summary>
+        /// <param name="files"></param>
+        /// <returns></returns>
+        private void ValidateUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files)
+        {
+            if (files == null)
+                throw new ArgumentNullException(nameof(files));
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void AfterUploadFilesDefaultImplementation(IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLog = false;
+            AfterUploadFiles(ref suppressDefaultLog, apiResponseLocalVar, files, petId);
+            if (!suppressDefaultLog)
+                Logger.LogInformation("{0,-9} | {1} | {2}", (apiResponseLocalVar.DownloadedAt - apiResponseLocalVar.RequestedAt).TotalSeconds, apiResponseLocalVar.StatusCode, apiResponseLocalVar.Path);
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="suppressDefaultLog"></param>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void AfterUploadFiles(ref bool suppressDefaultLog, IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// Logs exceptions that occur while retrieving the server response
+        /// </summary>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void OnErrorUploadFilesDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLogLocalVar = false;
+            OnErrorUploadFiles(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, files, petId);
+            if (!suppressDefaultLogLocalVar)
+                Logger.LogError(exceptionLocalVar, "An error occurred while sending the request to the server.");
+        }
+
+        /// <summary>
+        /// A partial method that gives developers a way to provide customized exception handling
+        /// </summary>
+        /// <param name="suppressDefaultLogLocalVar"></param>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void OnErrorUploadFiles(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            try
+            {
+                return await UploadFilesAsync(files, petId, cancellationToken).ConfigureAwait(false);
+            }
+            catch (Exception)
+            {
+                return null;
+            }
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            UriBuilder uriBuilderLocalVar = new UriBuilder();
+
+            try
+            {
+                ValidateUploadFiles(files);
+
+                FormatUploadFiles(files, ref petId);
+
+                using (HttpRequestMessage httpRequestMessageLocalVar = new HttpRequestMessage())
+                {
+                    uriBuilderLocalVar.Host = HttpClient.BaseAddress.Host;
+                    uriBuilderLocalVar.Port = HttpClient.BaseAddress.Port;
+                    uriBuilderLocalVar.Scheme = HttpClient.BaseAddress.Scheme;
+                    uriBuilderLocalVar.Path = HttpClient.BaseAddress.AbsolutePath == "/"
+                        ? "/pet/{petId}/uploadImages"
+                        : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImages");
+                    uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
+
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
+
+                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+
+                    List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
+
+                    foreach (Org.OpenAPITools.Client.FileParameter fileParameterLocalVar in files)
+                    {
+                        var streamContentLocalVar = new StreamContent(fileParameterLocalVar.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "files", fileParameterLocalVar.FileName ?? "files");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
+
+                    List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
+                    httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
+
+                    OAuthToken oauthTokenLocalVar1 = (OAuthToken) await OauthTokenProvider.GetAsync(cancellation: cancellationToken).ConfigureAwait(false);
+
+                    tokenBaseLocalVars.Add(oauthTokenLocalVar1);
+
+                    oauthTokenLocalVar1.UseInHeader(httpRequestMessageLocalVar, "");
+
+                    string[] contentTypes = new string[] {
+                        "multipart/form-data"
+                    };
+
+                    string[] acceptLocalVars = new string[] {
+                        "application/json"
+                    };
+
+                    IEnumerable<MediaTypeWithQualityHeaderValue> acceptHeaderValuesLocalVar = ClientUtils.SelectHeaderAcceptArray(acceptLocalVars);
+
+                    foreach (var acceptLocalVar in acceptHeaderValuesLocalVar)
+                        httpRequestMessageLocalVar.Headers.Accept.Add(acceptLocalVar);
+                    httpRequestMessageLocalVar.Method = new HttpMethod("POST");
+
+                    DateTime requestedAtLocalVar = DateTime.UtcNow;
+
+                    using (HttpResponseMessage httpResponseMessageLocalVar = await HttpClient.SendAsync(httpRequestMessageLocalVar, cancellationToken).ConfigureAwait(false))
+                    {
+                        ILogger<UploadFilesApiResponse> apiResponseLoggerLocalVar = LoggerFactory.CreateLogger<UploadFilesApiResponse>();
+                        UploadFilesApiResponse apiResponseLocalVar;
+
+                        switch ((int)httpResponseMessageLocalVar.StatusCode) {
+                            default: {
+                                string responseContentLocalVar = await httpResponseMessageLocalVar.Content.ReadAsStringAsync().ConfigureAwait(false);
+                                apiResponseLocalVar = new UploadFilesApiResponse(apiResponseLoggerLocalVar, httpRequestMessageLocalVar, httpResponseMessageLocalVar, responseContentLocalVar, "/pet/{petId}/uploadImages", requestedAtLocalVar, _jsonSerializerOptions);
+
+                                break;
+                            }
+                        }
+
+                        AfterUploadFilesDefaultImplementation(apiResponseLocalVar, files, petId);
+
+                        Events.ExecuteOnUploadFiles(apiResponseLocalVar);
+
+                        if (apiResponseLocalVar.StatusCode == (HttpStatusCode) 429)
+                            foreach(TokenBase tokenBaseLocalVar in tokenBaseLocalVars)
+                                tokenBaseLocalVar.BeginRateLimit();
+
+                        return apiResponseLocalVar;
+                    }
+                }
+            }
+            catch(Exception e)
+            {
+                OnErrorUploadFilesDefaultImplementation(e, "/pet/{petId}/uploadImages", uriBuilderLocalVar.Path, files, petId);
+                Events.ExecuteOnErrorUploadFiles(e);
+                throw;
+            }
+        }
+
+        /// <summary>
+        /// The <see cref="UploadFilesApiResponse"/>
+        /// </summary>
+        public partial class UploadFilesApiResponse : Org.OpenAPITools.Client.ApiResponse, IUploadFilesApiResponse
+        {
+            /// <summary>
+            /// The logger
+            /// </summary>
+            public ILogger<UploadFilesApiResponse> Logger { get; }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="rawContent"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, string rawContent, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, rawContent, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="contentStream"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, System.IO.Stream contentStream, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, contentStream, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            partial void OnCreated(global::System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage);
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public bool IsOk => 200 == (int)StatusCode;
+
+            /// <summary>
+            /// Deserializes the response if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public Org.OpenAPITools.Model.ApiResponse Ok()
+            {
+                // This logic may be modified with the AsModel.mustache template
+                return IsOk
+                    ? System.Text.Json.JsonSerializer.Deserialize<Org.OpenAPITools.Model.ApiResponse>(RawContent, _jsonSerializerOptions)
+                    : default;
+            }
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok and the deserialized response is not null
+            /// </summary>
+            /// <param name="result"></param>
+            /// <returns></returns>
+            public bool TryOk(out Org.OpenAPITools.Model.ApiResponse result)
+            {
+                result = null;
+
+                try
+                {
+                    result = Ok();
+                } catch (Exception e)
+                {
+                    OnDeserializationErrorDefaultImplementation(e, (HttpStatusCode)200);
+                }
+
+                return result != null;
+            }
+
+            private void OnDeserializationErrorDefaultImplementation(Exception exception, HttpStatusCode httpStatusCode)
+            {
+                bool suppressDefaultLog = false;
+                OnDeserializationError(ref suppressDefaultLog, exception, httpStatusCode);
+                if (!suppressDefaultLog)
+                    Logger.LogError(exception, "An error occurred while deserializing the {code} response.", httpStatusCode);
+            }
+
+            partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/net4.7/FormModels/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net4.7/FormModels/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..6150dbcf4774
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net4.7/FormModels/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,40 @@
+// <auto-generated>
+/*
+ * OpenAPI Petstore
+ *
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net4.7/OneOf/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net4.7/OneOf/.openapi-generator/FILES
index 47a388f55336..ef946be5e2fb 100644
--- a/samples/client/petstore/csharp/generichost/net4.7/OneOf/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net4.7/OneOf/.openapi-generator/FILES
@@ -24,6 +24,7 @@ src/Org.OpenAPITools/Client/CookieContainer.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/JsonSerializerOptionsProvider.cs
 src/Org.OpenAPITools/Client/Option.cs
diff --git a/samples/client/petstore/csharp/generichost/net4.7/OneOf/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net4.7/OneOf/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..5c8e0767f76a
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net4.7/OneOf/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,40 @@
+// <auto-generated>
+/*
+ * fruity
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * The version of the OpenAPI document: 0.0.1
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net4.7/Petstore/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net4.7/Petstore/.openapi-generator/FILES
index a6635c9d8351..82501a149e01 100644
--- a/samples/client/petstore/csharp/generichost/net4.7/Petstore/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net4.7/Petstore/.openapi-generator/FILES
@@ -138,6 +138,7 @@ src/Org.OpenAPITools/Client/CookieContainer.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningToken.cs
diff --git a/samples/client/petstore/csharp/generichost/net4.7/Petstore/api/openapi.yaml b/samples/client/petstore/csharp/generichost/net4.7/Petstore/api/openapi.yaml
index d8106a5755fc..ca451f3fb832 100644
--- a/samples/client/petstore/csharp/generichost/net4.7/Petstore/api/openapi.yaml
+++ b/samples/client/petstore/csharp/generichost/net4.7/Petstore/api/openapi.yaml
@@ -331,6 +331,40 @@ paths:
       summary: uploads an image
       tags:
       - pet
+  /pet/{petId}/uploadImages:
+    post:
+      description: ""
+      operationId: uploadFiles
+      parameters:
+      - description: ID of pet to update
+        explode: false
+        in: path
+        name: petId
+        required: true
+        schema:
+          format: int64
+          type: integer
+        style: simple
+      requestBody:
+        content:
+          multipart/form-data:
+            schema:
+              $ref: "#/components/schemas/uploadFiles_request"
+        required: true
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ApiResponse"
+          description: successful operation
+      security:
+      - petstore_auth:
+        - write:pets
+        - read:pets
+      summary: uploads an images
+      tags:
+      - pet
   /store/inventory:
     get:
       description: Returns a map of status codes to quantities
@@ -2924,6 +2958,16 @@ components:
           format: binary
           type: string
       type: object
+    uploadFiles_request:
+      properties:
+        files:
+          items:
+            format: binary
+            type: string
+          type: array
+      required:
+      - files
+      type: object
     testEnumParameters_request:
       properties:
         enum_form_string_array:
diff --git a/samples/client/petstore/csharp/generichost/net4.7/Petstore/docs/apis/PetApi.md b/samples/client/petstore/csharp/generichost/net4.7/Petstore/docs/apis/PetApi.md
index 2826ea00f728..b42ee516b313 100644
--- a/samples/client/petstore/csharp/generichost/net4.7/Petstore/docs/apis/PetApi.md
+++ b/samples/client/petstore/csharp/generichost/net4.7/Petstore/docs/apis/PetApi.md
@@ -13,6 +13,7 @@ All URIs are relative to *http://petstore.swagger.io:80/v2*
 | [**UpdatePetWithForm**](PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data |
 | [**UploadFile**](PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image |
 | [**UploadFileWithRequiredFile**](PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required) |
+| [**UploadFiles**](PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images |
 
 <a id="addpet"></a>
 # **AddPet**
@@ -341,3 +342,38 @@ uploads an image (required)
 
 [[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
 
+<a id="uploadfiles"></a>
+# **UploadFiles**
+> ApiResponse UploadFiles (List<System.IO.Stream> files, long petId)
+
+uploads an images
+
+
+### Parameters
+
+| Name | Type | Description | Notes |
+|------|------|-------------|-------|
+| **files** | **List&lt;System.IO.Stream&gt;** |  |  |
+| **petId** | **long** | ID of pet to update |  |
+
+### Return type
+
+[**ApiResponse**](ApiResponse.md)
+
+### Authorization
+
+[petstore_auth](../README.md#petstore_auth)
+
+### HTTP request headers
+
+ - **Content-Type**: multipart/form-data
+ - **Accept**: application/json
+
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **200** | successful operation |  -  |
+
+[[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
+
diff --git a/samples/client/petstore/csharp/generichost/net4.7/Petstore/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs b/samples/client/petstore/csharp/generichost/net4.7/Petstore/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
index ce85f85778ef..6420b47bc8b4 100644
--- a/samples/client/petstore/csharp/generichost/net4.7/Petstore/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/net4.7/Petstore/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
@@ -196,7 +196,7 @@ public async Task TestEndpointParametersAsyncTest()
             string patternWithoutDelimiter = default;
             byte[] varByte = default;
             double varDouble = default;
-            Client.Option<System.IO.Stream> binary = default;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> binary = default;
             Client.Option<string> callback = default;
             Client.Option<DateTime> date = default;
             Client.Option<DateTime> dateTime = default;
diff --git a/samples/client/petstore/csharp/generichost/net4.7/Petstore/src/Org.OpenAPITools.Test/Api/PetApiTests.cs b/samples/client/petstore/csharp/generichost/net4.7/Petstore/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
index 215e88093797..e9b05337bb59 100644
--- a/samples/client/petstore/csharp/generichost/net4.7/Petstore/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/net4.7/Petstore/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
@@ -137,7 +137,7 @@ public async Task UploadFileAsyncTest()
         {
             long petId = default;
             Client.Option<string> additionalMetadata = default;
-            Client.Option<System.IO.Stream> file = default;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> file = default;
             var response = await _instance.UploadFileAsync(petId, additionalMetadata, file);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
@@ -150,11 +150,24 @@ public async Task UploadFileAsyncTest()
         public async Task UploadFileWithRequiredFileAsyncTest()
         {
             long petId = default;
-            System.IO.Stream requiredFile = default;
+            Org.OpenAPITools.Client.FileParameter requiredFile = default;
             Client.Option<string> additionalMetadata = default;
             var response = await _instance.UploadFileWithRequiredFileAsync(petId, requiredFile, additionalMetadata);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
         }
+
+        /// <summary>
+        /// Test UploadFiles
+        /// </summary>
+        [Fact (Skip = "not implemented")]
+        public async Task UploadFilesAsyncTest()
+        {
+            List<Org.OpenAPITools.Client.FileParameter> files = default;
+            long petId = default;
+            var response = await _instance.UploadFilesAsync(files, petId);
+            var model = response.Ok();
+            Assert.IsType<ApiResponse>(model);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/net4.7/Petstore/src/Org.OpenAPITools/Api/DefaultApi.cs b/samples/client/petstore/csharp/generichost/net4.7/Petstore/src/Org.OpenAPITools/Api/DefaultApi.cs
index 1bbf43279f7c..24a69b84527e 100644
--- a/samples/client/petstore/csharp/generichost/net4.7/Petstore/src/Org.OpenAPITools/Api/DefaultApi.cs
+++ b/samples/client/petstore/csharp/generichost/net4.7/Petstore/src/Org.OpenAPITools/Api/DefaultApi.cs
@@ -763,27 +763,19 @@ public async Task<IGetCountryApiResponse> GetCountryAsync(string country, System
                         ? "/country"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/country");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("country", ClientUtils.ParameterToString(country)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = new HttpMethod("POST");
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/net4.7/Petstore/src/Org.OpenAPITools/Api/FakeApi.cs b/samples/client/petstore/csharp/generichost/net4.7/Petstore/src/Org.OpenAPITools/Api/FakeApi.cs
index feec543b8c1f..a3a842305a6f 100644
--- a/samples/client/petstore/csharp/generichost/net4.7/Petstore/src/Org.OpenAPITools/Api/FakeApi.cs
+++ b/samples/client/petstore/csharp/generichost/net4.7/Petstore/src/Org.OpenAPITools/Api/FakeApi.cs
@@ -330,7 +330,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -354,7 +354,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// To test enum parameters
@@ -4071,7 +4071,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<System.IO.Stream> binary, ref Option<string> callback, ref Option<DateTime> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
+        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<Org.OpenAPITools.Client.FileParameter> binary, ref Option<string> callback, ref Option<DateTime> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
 
         /// <summary>
         /// Validates the request parameters
@@ -4083,7 +4083,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="password"></param>
         /// <param name="varString"></param>
         /// <returns></returns>
-        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<System.IO.Stream> binary, Option<string> callback, Option<string> password, Option<string> varString)
+        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<string> password, Option<string> varString)
         {
             if (patternWithoutDelimiter == null)
                 throw new ArgumentNullException(nameof(patternWithoutDelimiter));
@@ -4122,7 +4122,7 @@ private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLog = false;
             AfterTestEndpointParameters(ref suppressDefaultLog, apiResponseLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4149,7 +4149,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -4171,7 +4171,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorTestEndpointParameters(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4200,7 +4200,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트  Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -4221,7 +4221,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -4253,7 +4253,7 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDe
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -4272,14 +4272,8 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         ? "/fake"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("number", ClientUtils.ParameterToString(number)));
 
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("pattern_without_delimiter", ClientUtils.ParameterToString(patternWithoutDelimiter)));
@@ -4289,7 +4283,7 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("double", ClientUtils.ParameterToString(varDouble)));
 
                     if (binary.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(binary.Value));
+                        throw new NotSupportedException("File parameters cannot be sent with application/x-www-form-urlencoded. Change the operation's content type to multipart/form-data.");
 
                     if (callback.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("callback", ClientUtils.ParameterToString(callback.Value)));
@@ -4318,6 +4312,9 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                     if (varString.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("string", ClientUtils.ParameterToString(varString.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -4331,11 +4328,6 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = new HttpMethod("POST");
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -4628,29 +4620,23 @@ public async Task<ITestEnumParametersApiResponse> TestEnumParametersAsync(Option
                     if (enumHeaderStringArray.IsSet)
                         httpRequestMessageLocalVar.Headers.Add("enum_header_string_array", ClientUtils.ParameterToString(enumHeaderStringArray.Value));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (enumFormString.IsSet)
+                    if (enumFormString.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("enum_form_string", ClientUtils.ParameterToString(enumFormString.Value)));
 
                     if (enumFormStringArray.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("enum_form_string_array", ClientUtils.ParameterToString(enumFormStringArray.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = new HttpMethod("GET");
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -5536,29 +5522,21 @@ public async Task<ITestJsonFormDataApiResponse> TestJsonFormDataAsync(string par
                         ? "/fake/jsonFormData"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/jsonFormData");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("param", ClientUtils.ParameterToString(param)));
 
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("param2", ClientUtils.ParameterToString(param2)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = new HttpMethod("GET");
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/net4.7/Petstore/src/Org.OpenAPITools/Api/PetApi.cs b/samples/client/petstore/csharp/generichost/net4.7/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
index 7fe162b51bfb..9d04b53a95c5 100644
--- a/samples/client/petstore/csharp/generichost/net4.7/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
+++ b/samples/client/petstore/csharp/generichost/net4.7/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
@@ -216,7 +216,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image
@@ -229,7 +229,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -243,7 +243,7 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -256,7 +256,32 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        Task<IUploadFilesApiResponse> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
     }
 
     /// <summary>
@@ -415,6 +440,18 @@ public interface IUploadFileWithRequiredFileApiResponse : Org.OpenAPITools.Clien
         bool IsOk { get; }
     }
 
+    /// <summary>
+    /// The <see cref="IUploadFilesApiResponse"/>
+    /// </summary>
+    public interface IUploadFilesApiResponse : Org.OpenAPITools.Client.IApiResponse, IOk<Org.OpenAPITools.Model.ApiResponse>
+    {
+        /// <summary>
+        /// Returns true if the response is 200 Ok
+        /// </summary>
+        /// <returns></returns>
+        bool IsOk { get; }
+    }
+
     /// <summary>
     /// Represents a collection of functions to interact with the API endpoints
     /// </summary>
@@ -599,6 +636,26 @@ internal void ExecuteOnErrorUploadFileWithRequiredFile(Exception exception)
         {
             OnErrorUploadFileWithRequiredFile?.Invoke(this, new ExceptionEventArgs(exception));
         }
+
+        /// <summary>
+        /// The event raised after the server response
+        /// </summary>
+        public event EventHandler<ApiResponseEventArgs> OnUploadFiles;
+
+        /// <summary>
+        /// The event raised after an error querying the server
+        /// </summary>
+        public event EventHandler<ExceptionEventArgs> OnErrorUploadFiles;
+
+        internal void ExecuteOnUploadFiles(PetApi.UploadFilesApiResponse apiResponse)
+        {
+            OnUploadFiles?.Invoke(this, new ApiResponseEventArgs(apiResponse));
+        }
+
+        internal void ExecuteOnErrorUploadFiles(Exception exception)
+        {
+            OnErrorUploadFiles?.Invoke(this, new ExceptionEventArgs(exception));
+        }
     }
 
     /// <summary>
@@ -2326,18 +2383,17 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (name.IsSet)
+                    if (name.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("name", ClientUtils.ParameterToString(name.Value)));
 
                     if (status.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("status", ClientUtils.ParameterToString(status.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -2351,11 +2407,6 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = new HttpMethod("POST");
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -2455,7 +2506,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<System.IO.Stream> file);
+        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Validates the request parameters
@@ -2463,7 +2514,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
         /// <returns></returns>
-        private void ValidateUploadFile(Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void ValidateUploadFile(Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             if (additionalMetadata.IsSet && additionalMetadata.Value == null)
                 throw new ArgumentNullException(nameof(additionalMetadata));
@@ -2479,7 +2530,7 @@ private void ValidateUploadFile(Option<string> additionalMetadata, Option<System
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLog = false;
             AfterUploadFile(ref suppressDefaultLog, apiResponseLocalVar, petId, additionalMetadata, file);
@@ -2495,7 +2546,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2506,7 +2557,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, additionalMetadata, file);
@@ -2524,7 +2575,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// uploads an image 
@@ -2534,7 +2585,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2555,7 +2606,7 @@ public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, O
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2575,17 +2626,23 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImage");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (additionalMetadata.IsSet)
+                    if (additionalMetadata.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
 
                     if (file.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(file.Value));
+                    {
+                        var streamContentLocalVar = new StreamContent(file.Value.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "file", file.Value.FileName ?? "file");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -2600,11 +2657,6 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         "multipart/form-data"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json"
                     };
@@ -2744,7 +2796,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFileWithRequiredFile(ref long petId, ref System.IO.Stream requiredFile, ref Option<string> additionalMetadata);
+        partial void FormatUploadFileWithRequiredFile(ref long petId, ref Org.OpenAPITools.Client.FileParameter requiredFile, ref Option<string> additionalMetadata);
 
         /// <summary>
         /// Validates the request parameters
@@ -2752,7 +2804,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
         /// <returns></returns>
-        private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void ValidateUploadFileWithRequiredFile(Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             if (requiredFile == null)
                 throw new ArgumentNullException(nameof(requiredFile));
@@ -2768,7 +2820,7 @@ private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, O
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLog = false;
             AfterUploadFileWithRequiredFile(ref suppressDefaultLog, apiResponseLocalVar, petId, requiredFile, additionalMetadata);
@@ -2784,7 +2836,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2795,7 +2847,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFileWithRequiredFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, requiredFile, additionalMetadata);
@@ -2813,7 +2865,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// uploads an image (required) 
@@ -2823,7 +2875,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2844,7 +2896,7 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2864,17 +2916,23 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/{petId}/uploadImageWithRequiredFile");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    multipartContentLocalVar.Add(new StreamContent(requiredFile));
+                    {
+                        var streamContentLocalVar = new StreamContent(requiredFile.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "requiredFile", requiredFile.FileName ?? "requiredFile");
+                    }
 
                     if (additionalMetadata.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
 
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -2888,11 +2946,6 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         "multipart/form-data"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json",
                         "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
@@ -3032,5 +3085,282 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
 
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
+
+        partial void FormatUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files, ref long petId);
+
+        /// <summary>
+        /// Validates the request parameters
+        /// </summary>
+        /// <param name="files"></param>
+        /// <returns></returns>
+        private void ValidateUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files)
+        {
+            if (files == null)
+                throw new ArgumentNullException(nameof(files));
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void AfterUploadFilesDefaultImplementation(IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLog = false;
+            AfterUploadFiles(ref suppressDefaultLog, apiResponseLocalVar, files, petId);
+            if (!suppressDefaultLog)
+                Logger.LogInformation("{0,-9} | {1} | {2}", (apiResponseLocalVar.DownloadedAt - apiResponseLocalVar.RequestedAt).TotalSeconds, apiResponseLocalVar.StatusCode, apiResponseLocalVar.Path);
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="suppressDefaultLog"></param>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void AfterUploadFiles(ref bool suppressDefaultLog, IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// Logs exceptions that occur while retrieving the server response
+        /// </summary>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void OnErrorUploadFilesDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLogLocalVar = false;
+            OnErrorUploadFiles(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, files, petId);
+            if (!suppressDefaultLogLocalVar)
+                Logger.LogError(exceptionLocalVar, "An error occurred while sending the request to the server.");
+        }
+
+        /// <summary>
+        /// A partial method that gives developers a way to provide customized exception handling
+        /// </summary>
+        /// <param name="suppressDefaultLogLocalVar"></param>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void OnErrorUploadFiles(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            try
+            {
+                return await UploadFilesAsync(files, petId, cancellationToken).ConfigureAwait(false);
+            }
+            catch (Exception)
+            {
+                return null;
+            }
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            UriBuilder uriBuilderLocalVar = new UriBuilder();
+
+            try
+            {
+                ValidateUploadFiles(files);
+
+                FormatUploadFiles(files, ref petId);
+
+                using (HttpRequestMessage httpRequestMessageLocalVar = new HttpRequestMessage())
+                {
+                    uriBuilderLocalVar.Host = HttpClient.BaseAddress.Host;
+                    uriBuilderLocalVar.Port = HttpClient.BaseAddress.Port;
+                    uriBuilderLocalVar.Scheme = HttpClient.BaseAddress.Scheme;
+                    uriBuilderLocalVar.Path = HttpClient.BaseAddress.AbsolutePath == "/"
+                        ? "/pet/{petId}/uploadImages"
+                        : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImages");
+                    uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
+
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
+
+                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+
+                    List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
+
+                    foreach (Org.OpenAPITools.Client.FileParameter fileParameterLocalVar in files)
+                    {
+                        var streamContentLocalVar = new StreamContent(fileParameterLocalVar.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "files", fileParameterLocalVar.FileName ?? "files");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
+
+                    List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
+                    httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
+
+                    OAuthToken oauthTokenLocalVar1 = (OAuthToken) await OauthTokenProvider.GetAsync(cancellation: cancellationToken).ConfigureAwait(false);
+
+                    tokenBaseLocalVars.Add(oauthTokenLocalVar1);
+
+                    oauthTokenLocalVar1.UseInHeader(httpRequestMessageLocalVar, "");
+
+                    string[] contentTypes = new string[] {
+                        "multipart/form-data"
+                    };
+
+                    string[] acceptLocalVars = new string[] {
+                        "application/json"
+                    };
+
+                    IEnumerable<MediaTypeWithQualityHeaderValue> acceptHeaderValuesLocalVar = ClientUtils.SelectHeaderAcceptArray(acceptLocalVars);
+
+                    foreach (var acceptLocalVar in acceptHeaderValuesLocalVar)
+                        httpRequestMessageLocalVar.Headers.Accept.Add(acceptLocalVar);
+                    httpRequestMessageLocalVar.Method = new HttpMethod("POST");
+
+                    DateTime requestedAtLocalVar = DateTime.UtcNow;
+
+                    using (HttpResponseMessage httpResponseMessageLocalVar = await HttpClient.SendAsync(httpRequestMessageLocalVar, cancellationToken).ConfigureAwait(false))
+                    {
+                        ILogger<UploadFilesApiResponse> apiResponseLoggerLocalVar = LoggerFactory.CreateLogger<UploadFilesApiResponse>();
+                        UploadFilesApiResponse apiResponseLocalVar;
+
+                        switch ((int)httpResponseMessageLocalVar.StatusCode) {
+                            default: {
+                                string responseContentLocalVar = await httpResponseMessageLocalVar.Content.ReadAsStringAsync().ConfigureAwait(false);
+                                apiResponseLocalVar = new UploadFilesApiResponse(apiResponseLoggerLocalVar, httpRequestMessageLocalVar, httpResponseMessageLocalVar, responseContentLocalVar, "/pet/{petId}/uploadImages", requestedAtLocalVar, _jsonSerializerOptions);
+
+                                break;
+                            }
+                        }
+
+                        AfterUploadFilesDefaultImplementation(apiResponseLocalVar, files, petId);
+
+                        Events.ExecuteOnUploadFiles(apiResponseLocalVar);
+
+                        if (apiResponseLocalVar.StatusCode == (HttpStatusCode) 429)
+                            foreach(TokenBase tokenBaseLocalVar in tokenBaseLocalVars)
+                                tokenBaseLocalVar.BeginRateLimit();
+
+                        return apiResponseLocalVar;
+                    }
+                }
+            }
+            catch(Exception e)
+            {
+                OnErrorUploadFilesDefaultImplementation(e, "/pet/{petId}/uploadImages", uriBuilderLocalVar.Path, files, petId);
+                Events.ExecuteOnErrorUploadFiles(e);
+                throw;
+            }
+        }
+
+        /// <summary>
+        /// The <see cref="UploadFilesApiResponse"/>
+        /// </summary>
+        public partial class UploadFilesApiResponse : Org.OpenAPITools.Client.ApiResponse, IUploadFilesApiResponse
+        {
+            /// <summary>
+            /// The logger
+            /// </summary>
+            public ILogger<UploadFilesApiResponse> Logger { get; }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="rawContent"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, string rawContent, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, rawContent, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="contentStream"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, System.IO.Stream contentStream, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, contentStream, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            partial void OnCreated(global::System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage);
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public bool IsOk => 200 == (int)StatusCode;
+
+            /// <summary>
+            /// Deserializes the response if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public Org.OpenAPITools.Model.ApiResponse Ok()
+            {
+                // This logic may be modified with the AsModel.mustache template
+                return IsOk
+                    ? System.Text.Json.JsonSerializer.Deserialize<Org.OpenAPITools.Model.ApiResponse>(RawContent, _jsonSerializerOptions)
+                    : default;
+            }
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok and the deserialized response is not null
+            /// </summary>
+            /// <param name="result"></param>
+            /// <returns></returns>
+            public bool TryOk(out Org.OpenAPITools.Model.ApiResponse result)
+            {
+                result = null;
+
+                try
+                {
+                    result = Ok();
+                } catch (Exception e)
+                {
+                    OnDeserializationErrorDefaultImplementation(e, (HttpStatusCode)200);
+                }
+
+                return result != null;
+            }
+
+            private void OnDeserializationErrorDefaultImplementation(Exception exception, HttpStatusCode httpStatusCode)
+            {
+                bool suppressDefaultLog = false;
+                OnDeserializationError(ref suppressDefaultLog, exception, httpStatusCode);
+                if (!suppressDefaultLog)
+                    Logger.LogError(exception, "An error occurred while deserializing the {code} response.", httpStatusCode);
+            }
+
+            partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/net4.7/Petstore/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net4.7/Petstore/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..6150dbcf4774
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net4.7/Petstore/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,40 @@
+// <auto-generated>
+/*
+ * OpenAPI Petstore
+ *
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net4.7/UseDateTimeForDate/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net4.7/UseDateTimeForDate/.openapi-generator/FILES
index 5abbcf46f35c..e28da391730f 100644
--- a/samples/client/petstore/csharp/generichost/net4.7/UseDateTimeForDate/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net4.7/UseDateTimeForDate/.openapi-generator/FILES
@@ -21,6 +21,7 @@ src/Org.OpenAPITools/Client/CookieContainer.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/JsonSerializerOptionsProvider.cs
 src/Org.OpenAPITools/Client/Option.cs
diff --git a/samples/client/petstore/csharp/generichost/net4.7/UseDateTimeForDate/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net4.7/UseDateTimeForDate/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..253a70bc8053
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net4.7/UseDateTimeForDate/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,40 @@
+// <auto-generated>
+/*
+ * OpenAPI Dates
+ *
+ * Thic spec contains endpoints with dates in different formats
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net4.8/AllOf/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net4.8/AllOf/.openapi-generator/FILES
index 47b2b9b5c4f4..1c80f1449c66 100644
--- a/samples/client/petstore/csharp/generichost/net4.8/AllOf/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net4.8/AllOf/.openapi-generator/FILES
@@ -23,6 +23,7 @@ src/Org.OpenAPITools/Client/CookieContainer.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/JsonSerializerOptionsProvider.cs
 src/Org.OpenAPITools/Client/Option.cs
diff --git a/samples/client/petstore/csharp/generichost/net4.8/AllOf/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net4.8/AllOf/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..936f8415fda6
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net4.8/AllOf/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,40 @@
+// <auto-generated>
+/*
+ * Example
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net4.8/AnyOf/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net4.8/AnyOf/.openapi-generator/FILES
index 59cc1ea25a08..5e82fcb80ae5 100644
--- a/samples/client/petstore/csharp/generichost/net4.8/AnyOf/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net4.8/AnyOf/.openapi-generator/FILES
@@ -23,6 +23,7 @@ src/Org.OpenAPITools/Client/CookieContainer.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/JsonSerializerOptionsProvider.cs
 src/Org.OpenAPITools/Client/Option.cs
diff --git a/samples/client/petstore/csharp/generichost/net4.8/AnyOf/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net4.8/AnyOf/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..5c8e0767f76a
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net4.8/AnyOf/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,40 @@
+// <auto-generated>
+/*
+ * fruity
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * The version of the OpenAPI document: 0.0.1
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net4.8/AnyOfNoCompare/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net4.8/AnyOfNoCompare/.openapi-generator/FILES
index 59cc1ea25a08..5e82fcb80ae5 100644
--- a/samples/client/petstore/csharp/generichost/net4.8/AnyOfNoCompare/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net4.8/AnyOfNoCompare/.openapi-generator/FILES
@@ -23,6 +23,7 @@ src/Org.OpenAPITools/Client/CookieContainer.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/JsonSerializerOptionsProvider.cs
 src/Org.OpenAPITools/Client/Option.cs
diff --git a/samples/client/petstore/csharp/generichost/net4.8/AnyOfNoCompare/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net4.8/AnyOfNoCompare/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..5c8e0767f76a
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net4.8/AnyOfNoCompare/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,40 @@
+// <auto-generated>
+/*
+ * fruity
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * The version of the OpenAPI document: 0.0.1
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net4.8/FormModels/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net4.8/FormModels/.openapi-generator/FILES
index 3c592107ec19..4d9b3d8248d3 100644
--- a/samples/client/petstore/csharp/generichost/net4.8/FormModels/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net4.8/FormModels/.openapi-generator/FILES
@@ -163,6 +163,7 @@ src/Org.OpenAPITools/Client/CookieContainer.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningToken.cs
diff --git a/samples/client/petstore/csharp/generichost/net4.8/FormModels/api/openapi.yaml b/samples/client/petstore/csharp/generichost/net4.8/FormModels/api/openapi.yaml
index a9ab8dd51c13..7017affc0b9c 100644
--- a/samples/client/petstore/csharp/generichost/net4.8/FormModels/api/openapi.yaml
+++ b/samples/client/petstore/csharp/generichost/net4.8/FormModels/api/openapi.yaml
@@ -326,6 +326,40 @@ paths:
       summary: uploads an image
       tags:
       - pet
+  /pet/{petId}/uploadImages:
+    post:
+      description: ""
+      operationId: uploadFiles
+      parameters:
+      - description: ID of pet to update
+        explode: false
+        in: path
+        name: petId
+        required: true
+        schema:
+          format: int64
+          type: integer
+        style: simple
+      requestBody:
+        content:
+          multipart/form-data:
+            schema:
+              $ref: "#/components/schemas/uploadFiles_request"
+        required: true
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ApiResponse"
+          description: successful operation
+      security:
+      - petstore_auth:
+        - write:pets
+        - read:pets
+      summary: uploads an images
+      tags:
+      - pet
   /store/inventory:
     get:
       description: Returns a map of status codes to quantities
@@ -2748,6 +2782,16 @@ components:
           format: binary
           type: string
       type: object
+    uploadFiles_request:
+      properties:
+        files:
+          items:
+            format: binary
+            type: string
+          type: array
+      required:
+      - files
+      type: object
     testEnumParameters_request_enum_form_string_array_inner:
       default: $
       enum:
diff --git a/samples/client/petstore/csharp/generichost/net4.8/FormModels/docs/apis/PetApi.md b/samples/client/petstore/csharp/generichost/net4.8/FormModels/docs/apis/PetApi.md
index e32c1e31e089..59d4ef8e6df0 100644
--- a/samples/client/petstore/csharp/generichost/net4.8/FormModels/docs/apis/PetApi.md
+++ b/samples/client/petstore/csharp/generichost/net4.8/FormModels/docs/apis/PetApi.md
@@ -13,6 +13,7 @@ All URIs are relative to *http://petstore.swagger.io:80/v2*
 | [**UpdatePetWithForm**](PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data |
 | [**UploadFile**](PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image |
 | [**UploadFileWithRequiredFile**](PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required) |
+| [**UploadFiles**](PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images |
 
 <a id="addpet"></a>
 # **AddPet**
@@ -341,3 +342,38 @@ uploads an image (required)
 
 [[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
 
+<a id="uploadfiles"></a>
+# **UploadFiles**
+> ApiResponse UploadFiles (List<System.IO.Stream> files, long petId)
+
+uploads an images
+
+
+### Parameters
+
+| Name | Type | Description | Notes |
+|------|------|-------------|-------|
+| **files** | **List&lt;System.IO.Stream&gt;** |  |  |
+| **petId** | **long** | ID of pet to update |  |
+
+### Return type
+
+[**ApiResponse**](ApiResponse.md)
+
+### Authorization
+
+[petstore_auth](../README.md#petstore_auth)
+
+### HTTP request headers
+
+ - **Content-Type**: multipart/form-data
+ - **Accept**: application/json
+
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **200** | successful operation |  -  |
+
+[[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
+
diff --git a/samples/client/petstore/csharp/generichost/net4.8/FormModels/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs b/samples/client/petstore/csharp/generichost/net4.8/FormModels/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
index dbca7881df47..62c158ea45da 100644
--- a/samples/client/petstore/csharp/generichost/net4.8/FormModels/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/net4.8/FormModels/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
@@ -196,7 +196,7 @@ public async Task TestEndpointParametersAsyncTest()
             string patternWithoutDelimiter = default;
             byte[] varByte = default;
             double varDouble = default;
-            Client.Option<System.IO.Stream> binary = default;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> binary = default;
             Client.Option<string> callback = default;
             Client.Option<DateTime> date = default;
             Client.Option<DateTime> dateTime = default;
diff --git a/samples/client/petstore/csharp/generichost/net4.8/FormModels/src/Org.OpenAPITools.Test/Api/PetApiTests.cs b/samples/client/petstore/csharp/generichost/net4.8/FormModels/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
index 1f1d7f6c4576..a4aa8f3e245d 100644
--- a/samples/client/petstore/csharp/generichost/net4.8/FormModels/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/net4.8/FormModels/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
@@ -137,7 +137,7 @@ public async Task UploadFileAsyncTest()
         {
             long petId = default;
             Client.Option<string> additionalMetadata = default;
-            Client.Option<System.IO.Stream> file = default;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> file = default;
             var response = await _instance.UploadFileAsync(petId, additionalMetadata, file);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
@@ -150,11 +150,24 @@ public async Task UploadFileAsyncTest()
         public async Task UploadFileWithRequiredFileAsyncTest()
         {
             long petId = default;
-            System.IO.Stream requiredFile = default;
+            Org.OpenAPITools.Client.FileParameter requiredFile = default;
             Client.Option<string> additionalMetadata = default;
             var response = await _instance.UploadFileWithRequiredFileAsync(petId, requiredFile, additionalMetadata);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
         }
+
+        /// <summary>
+        /// Test UploadFiles
+        /// </summary>
+        [Fact (Skip = "not implemented")]
+        public async Task UploadFilesAsyncTest()
+        {
+            List<Org.OpenAPITools.Client.FileParameter> files = default;
+            long petId = default;
+            var response = await _instance.UploadFilesAsync(files, petId);
+            var model = response.Ok();
+            Assert.IsType<ApiResponse>(model);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/net4.8/FormModels/src/Org.OpenAPITools/Api/DefaultApi.cs b/samples/client/petstore/csharp/generichost/net4.8/FormModels/src/Org.OpenAPITools/Api/DefaultApi.cs
index 1bbf43279f7c..24a69b84527e 100644
--- a/samples/client/petstore/csharp/generichost/net4.8/FormModels/src/Org.OpenAPITools/Api/DefaultApi.cs
+++ b/samples/client/petstore/csharp/generichost/net4.8/FormModels/src/Org.OpenAPITools/Api/DefaultApi.cs
@@ -763,27 +763,19 @@ public async Task<IGetCountryApiResponse> GetCountryAsync(string country, System
                         ? "/country"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/country");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("country", ClientUtils.ParameterToString(country)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = new HttpMethod("POST");
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/net4.8/FormModels/src/Org.OpenAPITools/Api/FakeApi.cs b/samples/client/petstore/csharp/generichost/net4.8/FormModels/src/Org.OpenAPITools/Api/FakeApi.cs
index ed9c440bd2b8..9f2605d1777f 100644
--- a/samples/client/petstore/csharp/generichost/net4.8/FormModels/src/Org.OpenAPITools/Api/FakeApi.cs
+++ b/samples/client/petstore/csharp/generichost/net4.8/FormModels/src/Org.OpenAPITools/Api/FakeApi.cs
@@ -330,7 +330,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -354,7 +354,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// To test enum parameters
@@ -4071,7 +4071,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<System.IO.Stream> binary, ref Option<string> callback, ref Option<DateTime> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
+        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<Org.OpenAPITools.Client.FileParameter> binary, ref Option<string> callback, ref Option<DateTime> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
 
         /// <summary>
         /// Validates the request parameters
@@ -4083,7 +4083,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="password"></param>
         /// <param name="varString"></param>
         /// <returns></returns>
-        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<System.IO.Stream> binary, Option<string> callback, Option<string> password, Option<string> varString)
+        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<string> password, Option<string> varString)
         {
             if (patternWithoutDelimiter == null)
                 throw new ArgumentNullException(nameof(patternWithoutDelimiter));
@@ -4122,7 +4122,7 @@ private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLog = false;
             AfterTestEndpointParameters(ref suppressDefaultLog, apiResponseLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4149,7 +4149,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -4171,7 +4171,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorTestEndpointParameters(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4200,7 +4200,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트  Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -4221,7 +4221,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -4253,7 +4253,7 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDe
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -4272,14 +4272,8 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         ? "/fake"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("number", ClientUtils.ParameterToString(number)));
 
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("pattern_without_delimiter", ClientUtils.ParameterToString(patternWithoutDelimiter)));
@@ -4289,7 +4283,7 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("double", ClientUtils.ParameterToString(varDouble)));
 
                     if (binary.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(binary.Value));
+                        throw new NotSupportedException("File parameters cannot be sent with application/x-www-form-urlencoded. Change the operation's content type to multipart/form-data.");
 
                     if (callback.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("callback", ClientUtils.ParameterToString(callback.Value)));
@@ -4318,6 +4312,9 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                     if (varString.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("string", ClientUtils.ParameterToString(varString.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -4331,11 +4328,6 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = new HttpMethod("POST");
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -4616,29 +4608,23 @@ public async Task<ITestEnumParametersApiResponse> TestEnumParametersAsync(Option
                     if (enumHeaderStringArray.IsSet)
                         httpRequestMessageLocalVar.Headers.Add("enum_header_string_array", ClientUtils.ParameterToString(enumHeaderStringArray.Value));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (enumFormString.IsSet)
+                    if (enumFormString.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("enum_form_string", ClientUtils.ParameterToString(enumFormString.Value)));
 
                     if (enumFormStringArray.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("enum_form_string_array", ClientUtils.ParameterToString(enumFormStringArray.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = new HttpMethod("GET");
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -5524,29 +5510,21 @@ public async Task<ITestJsonFormDataApiResponse> TestJsonFormDataAsync(string par
                         ? "/fake/jsonFormData"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/jsonFormData");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("param", ClientUtils.ParameterToString(param)));
 
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("param2", ClientUtils.ParameterToString(param2)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = new HttpMethod("GET");
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/net4.8/FormModels/src/Org.OpenAPITools/Api/PetApi.cs b/samples/client/petstore/csharp/generichost/net4.8/FormModels/src/Org.OpenAPITools/Api/PetApi.cs
index 0eaf83e1f41e..11f4b994064c 100644
--- a/samples/client/petstore/csharp/generichost/net4.8/FormModels/src/Org.OpenAPITools/Api/PetApi.cs
+++ b/samples/client/petstore/csharp/generichost/net4.8/FormModels/src/Org.OpenAPITools/Api/PetApi.cs
@@ -216,7 +216,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image
@@ -229,7 +229,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -243,7 +243,7 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -256,7 +256,32 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        Task<IUploadFilesApiResponse> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
     }
 
     /// <summary>
@@ -415,6 +440,18 @@ public interface IUploadFileWithRequiredFileApiResponse : Org.OpenAPITools.Clien
         bool IsOk { get; }
     }
 
+    /// <summary>
+    /// The <see cref="IUploadFilesApiResponse"/>
+    /// </summary>
+    public interface IUploadFilesApiResponse : Org.OpenAPITools.Client.IApiResponse, IOk<Org.OpenAPITools.Model.ApiResponse>
+    {
+        /// <summary>
+        /// Returns true if the response is 200 Ok
+        /// </summary>
+        /// <returns></returns>
+        bool IsOk { get; }
+    }
+
     /// <summary>
     /// Represents a collection of functions to interact with the API endpoints
     /// </summary>
@@ -599,6 +636,26 @@ internal void ExecuteOnErrorUploadFileWithRequiredFile(Exception exception)
         {
             OnErrorUploadFileWithRequiredFile?.Invoke(this, new ExceptionEventArgs(exception));
         }
+
+        /// <summary>
+        /// The event raised after the server response
+        /// </summary>
+        public event EventHandler<ApiResponseEventArgs> OnUploadFiles;
+
+        /// <summary>
+        /// The event raised after an error querying the server
+        /// </summary>
+        public event EventHandler<ExceptionEventArgs> OnErrorUploadFiles;
+
+        internal void ExecuteOnUploadFiles(PetApi.UploadFilesApiResponse apiResponse)
+        {
+            OnUploadFiles?.Invoke(this, new ApiResponseEventArgs(apiResponse));
+        }
+
+        internal void ExecuteOnErrorUploadFiles(Exception exception)
+        {
+            OnErrorUploadFiles?.Invoke(this, new ExceptionEventArgs(exception));
+        }
     }
 
     /// <summary>
@@ -2326,18 +2383,17 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (name.IsSet)
+                    if (name.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("name", ClientUtils.ParameterToString(name.Value)));
 
                     if (status.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("status", ClientUtils.ParameterToString(status.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -2351,11 +2407,6 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = new HttpMethod("POST");
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -2455,7 +2506,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<System.IO.Stream> file);
+        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Validates the request parameters
@@ -2463,7 +2514,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
         /// <returns></returns>
-        private void ValidateUploadFile(Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void ValidateUploadFile(Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             if (additionalMetadata.IsSet && additionalMetadata.Value == null)
                 throw new ArgumentNullException(nameof(additionalMetadata));
@@ -2479,7 +2530,7 @@ private void ValidateUploadFile(Option<string> additionalMetadata, Option<System
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLog = false;
             AfterUploadFile(ref suppressDefaultLog, apiResponseLocalVar, petId, additionalMetadata, file);
@@ -2495,7 +2546,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2506,7 +2557,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, additionalMetadata, file);
@@ -2524,7 +2575,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// uploads an image 
@@ -2534,7 +2585,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2555,7 +2606,7 @@ public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, O
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2575,17 +2626,23 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImage");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (additionalMetadata.IsSet)
+                    if (additionalMetadata.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
 
                     if (file.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(file.Value));
+                    {
+                        var streamContentLocalVar = new StreamContent(file.Value.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "file", file.Value.FileName ?? "file");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -2600,11 +2657,6 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         "multipart/form-data"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json"
                     };
@@ -2744,7 +2796,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFileWithRequiredFile(ref long petId, ref System.IO.Stream requiredFile, ref Option<string> additionalMetadata);
+        partial void FormatUploadFileWithRequiredFile(ref long petId, ref Org.OpenAPITools.Client.FileParameter requiredFile, ref Option<string> additionalMetadata);
 
         /// <summary>
         /// Validates the request parameters
@@ -2752,7 +2804,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
         /// <returns></returns>
-        private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void ValidateUploadFileWithRequiredFile(Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             if (requiredFile == null)
                 throw new ArgumentNullException(nameof(requiredFile));
@@ -2768,7 +2820,7 @@ private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, O
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLog = false;
             AfterUploadFileWithRequiredFile(ref suppressDefaultLog, apiResponseLocalVar, petId, requiredFile, additionalMetadata);
@@ -2784,7 +2836,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2795,7 +2847,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFileWithRequiredFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, requiredFile, additionalMetadata);
@@ -2813,7 +2865,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// uploads an image (required) 
@@ -2823,7 +2875,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2844,7 +2896,7 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2864,17 +2916,23 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/{petId}/uploadImageWithRequiredFile");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    multipartContentLocalVar.Add(new StreamContent(requiredFile));
+                    {
+                        var streamContentLocalVar = new StreamContent(requiredFile.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "requiredFile", requiredFile.FileName ?? "requiredFile");
+                    }
 
                     if (additionalMetadata.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
 
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -2888,11 +2946,6 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         "multipart/form-data"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json",
                         "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
@@ -3032,5 +3085,282 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
 
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
+
+        partial void FormatUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files, ref long petId);
+
+        /// <summary>
+        /// Validates the request parameters
+        /// </summary>
+        /// <param name="files"></param>
+        /// <returns></returns>
+        private void ValidateUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files)
+        {
+            if (files == null)
+                throw new ArgumentNullException(nameof(files));
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void AfterUploadFilesDefaultImplementation(IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLog = false;
+            AfterUploadFiles(ref suppressDefaultLog, apiResponseLocalVar, files, petId);
+            if (!suppressDefaultLog)
+                Logger.LogInformation("{0,-9} | {1} | {2}", (apiResponseLocalVar.DownloadedAt - apiResponseLocalVar.RequestedAt).TotalSeconds, apiResponseLocalVar.StatusCode, apiResponseLocalVar.Path);
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="suppressDefaultLog"></param>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void AfterUploadFiles(ref bool suppressDefaultLog, IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// Logs exceptions that occur while retrieving the server response
+        /// </summary>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void OnErrorUploadFilesDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLogLocalVar = false;
+            OnErrorUploadFiles(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, files, petId);
+            if (!suppressDefaultLogLocalVar)
+                Logger.LogError(exceptionLocalVar, "An error occurred while sending the request to the server.");
+        }
+
+        /// <summary>
+        /// A partial method that gives developers a way to provide customized exception handling
+        /// </summary>
+        /// <param name="suppressDefaultLogLocalVar"></param>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void OnErrorUploadFiles(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            try
+            {
+                return await UploadFilesAsync(files, petId, cancellationToken).ConfigureAwait(false);
+            }
+            catch (Exception)
+            {
+                return null;
+            }
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            UriBuilder uriBuilderLocalVar = new UriBuilder();
+
+            try
+            {
+                ValidateUploadFiles(files);
+
+                FormatUploadFiles(files, ref petId);
+
+                using (HttpRequestMessage httpRequestMessageLocalVar = new HttpRequestMessage())
+                {
+                    uriBuilderLocalVar.Host = HttpClient.BaseAddress.Host;
+                    uriBuilderLocalVar.Port = HttpClient.BaseAddress.Port;
+                    uriBuilderLocalVar.Scheme = HttpClient.BaseAddress.Scheme;
+                    uriBuilderLocalVar.Path = HttpClient.BaseAddress.AbsolutePath == "/"
+                        ? "/pet/{petId}/uploadImages"
+                        : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImages");
+                    uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
+
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
+
+                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+
+                    List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
+
+                    foreach (Org.OpenAPITools.Client.FileParameter fileParameterLocalVar in files)
+                    {
+                        var streamContentLocalVar = new StreamContent(fileParameterLocalVar.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "files", fileParameterLocalVar.FileName ?? "files");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
+
+                    List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
+                    httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
+
+                    OAuthToken oauthTokenLocalVar1 = (OAuthToken) await OauthTokenProvider.GetAsync(cancellation: cancellationToken).ConfigureAwait(false);
+
+                    tokenBaseLocalVars.Add(oauthTokenLocalVar1);
+
+                    oauthTokenLocalVar1.UseInHeader(httpRequestMessageLocalVar, "");
+
+                    string[] contentTypes = new string[] {
+                        "multipart/form-data"
+                    };
+
+                    string[] acceptLocalVars = new string[] {
+                        "application/json"
+                    };
+
+                    IEnumerable<MediaTypeWithQualityHeaderValue> acceptHeaderValuesLocalVar = ClientUtils.SelectHeaderAcceptArray(acceptLocalVars);
+
+                    foreach (var acceptLocalVar in acceptHeaderValuesLocalVar)
+                        httpRequestMessageLocalVar.Headers.Accept.Add(acceptLocalVar);
+                    httpRequestMessageLocalVar.Method = new HttpMethod("POST");
+
+                    DateTime requestedAtLocalVar = DateTime.UtcNow;
+
+                    using (HttpResponseMessage httpResponseMessageLocalVar = await HttpClient.SendAsync(httpRequestMessageLocalVar, cancellationToken).ConfigureAwait(false))
+                    {
+                        ILogger<UploadFilesApiResponse> apiResponseLoggerLocalVar = LoggerFactory.CreateLogger<UploadFilesApiResponse>();
+                        UploadFilesApiResponse apiResponseLocalVar;
+
+                        switch ((int)httpResponseMessageLocalVar.StatusCode) {
+                            default: {
+                                string responseContentLocalVar = await httpResponseMessageLocalVar.Content.ReadAsStringAsync().ConfigureAwait(false);
+                                apiResponseLocalVar = new UploadFilesApiResponse(apiResponseLoggerLocalVar, httpRequestMessageLocalVar, httpResponseMessageLocalVar, responseContentLocalVar, "/pet/{petId}/uploadImages", requestedAtLocalVar, _jsonSerializerOptions);
+
+                                break;
+                            }
+                        }
+
+                        AfterUploadFilesDefaultImplementation(apiResponseLocalVar, files, petId);
+
+                        Events.ExecuteOnUploadFiles(apiResponseLocalVar);
+
+                        if (apiResponseLocalVar.StatusCode == (HttpStatusCode) 429)
+                            foreach(TokenBase tokenBaseLocalVar in tokenBaseLocalVars)
+                                tokenBaseLocalVar.BeginRateLimit();
+
+                        return apiResponseLocalVar;
+                    }
+                }
+            }
+            catch(Exception e)
+            {
+                OnErrorUploadFilesDefaultImplementation(e, "/pet/{petId}/uploadImages", uriBuilderLocalVar.Path, files, petId);
+                Events.ExecuteOnErrorUploadFiles(e);
+                throw;
+            }
+        }
+
+        /// <summary>
+        /// The <see cref="UploadFilesApiResponse"/>
+        /// </summary>
+        public partial class UploadFilesApiResponse : Org.OpenAPITools.Client.ApiResponse, IUploadFilesApiResponse
+        {
+            /// <summary>
+            /// The logger
+            /// </summary>
+            public ILogger<UploadFilesApiResponse> Logger { get; }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="rawContent"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, string rawContent, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, rawContent, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="contentStream"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, System.IO.Stream contentStream, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, contentStream, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            partial void OnCreated(global::System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage);
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public bool IsOk => 200 == (int)StatusCode;
+
+            /// <summary>
+            /// Deserializes the response if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public Org.OpenAPITools.Model.ApiResponse Ok()
+            {
+                // This logic may be modified with the AsModel.mustache template
+                return IsOk
+                    ? System.Text.Json.JsonSerializer.Deserialize<Org.OpenAPITools.Model.ApiResponse>(RawContent, _jsonSerializerOptions)
+                    : default;
+            }
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok and the deserialized response is not null
+            /// </summary>
+            /// <param name="result"></param>
+            /// <returns></returns>
+            public bool TryOk(out Org.OpenAPITools.Model.ApiResponse result)
+            {
+                result = null;
+
+                try
+                {
+                    result = Ok();
+                } catch (Exception e)
+                {
+                    OnDeserializationErrorDefaultImplementation(e, (HttpStatusCode)200);
+                }
+
+                return result != null;
+            }
+
+            private void OnDeserializationErrorDefaultImplementation(Exception exception, HttpStatusCode httpStatusCode)
+            {
+                bool suppressDefaultLog = false;
+                OnDeserializationError(ref suppressDefaultLog, exception, httpStatusCode);
+                if (!suppressDefaultLog)
+                    Logger.LogError(exception, "An error occurred while deserializing the {code} response.", httpStatusCode);
+            }
+
+            partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/net4.8/FormModels/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net4.8/FormModels/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..6150dbcf4774
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net4.8/FormModels/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,40 @@
+// <auto-generated>
+/*
+ * OpenAPI Petstore
+ *
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net4.8/OneOf/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net4.8/OneOf/.openapi-generator/FILES
index 47a388f55336..ef946be5e2fb 100644
--- a/samples/client/petstore/csharp/generichost/net4.8/OneOf/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net4.8/OneOf/.openapi-generator/FILES
@@ -24,6 +24,7 @@ src/Org.OpenAPITools/Client/CookieContainer.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/JsonSerializerOptionsProvider.cs
 src/Org.OpenAPITools/Client/Option.cs
diff --git a/samples/client/petstore/csharp/generichost/net4.8/OneOf/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net4.8/OneOf/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..5c8e0767f76a
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net4.8/OneOf/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,40 @@
+// <auto-generated>
+/*
+ * fruity
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * The version of the OpenAPI document: 0.0.1
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net4.8/Petstore/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net4.8/Petstore/.openapi-generator/FILES
index a6635c9d8351..82501a149e01 100644
--- a/samples/client/petstore/csharp/generichost/net4.8/Petstore/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net4.8/Petstore/.openapi-generator/FILES
@@ -138,6 +138,7 @@ src/Org.OpenAPITools/Client/CookieContainer.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningToken.cs
diff --git a/samples/client/petstore/csharp/generichost/net4.8/Petstore/api/openapi.yaml b/samples/client/petstore/csharp/generichost/net4.8/Petstore/api/openapi.yaml
index d8106a5755fc..ca451f3fb832 100644
--- a/samples/client/petstore/csharp/generichost/net4.8/Petstore/api/openapi.yaml
+++ b/samples/client/petstore/csharp/generichost/net4.8/Petstore/api/openapi.yaml
@@ -331,6 +331,40 @@ paths:
       summary: uploads an image
       tags:
       - pet
+  /pet/{petId}/uploadImages:
+    post:
+      description: ""
+      operationId: uploadFiles
+      parameters:
+      - description: ID of pet to update
+        explode: false
+        in: path
+        name: petId
+        required: true
+        schema:
+          format: int64
+          type: integer
+        style: simple
+      requestBody:
+        content:
+          multipart/form-data:
+            schema:
+              $ref: "#/components/schemas/uploadFiles_request"
+        required: true
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ApiResponse"
+          description: successful operation
+      security:
+      - petstore_auth:
+        - write:pets
+        - read:pets
+      summary: uploads an images
+      tags:
+      - pet
   /store/inventory:
     get:
       description: Returns a map of status codes to quantities
@@ -2924,6 +2958,16 @@ components:
           format: binary
           type: string
       type: object
+    uploadFiles_request:
+      properties:
+        files:
+          items:
+            format: binary
+            type: string
+          type: array
+      required:
+      - files
+      type: object
     testEnumParameters_request:
       properties:
         enum_form_string_array:
diff --git a/samples/client/petstore/csharp/generichost/net4.8/Petstore/docs/apis/PetApi.md b/samples/client/petstore/csharp/generichost/net4.8/Petstore/docs/apis/PetApi.md
index 2826ea00f728..b42ee516b313 100644
--- a/samples/client/petstore/csharp/generichost/net4.8/Petstore/docs/apis/PetApi.md
+++ b/samples/client/petstore/csharp/generichost/net4.8/Petstore/docs/apis/PetApi.md
@@ -13,6 +13,7 @@ All URIs are relative to *http://petstore.swagger.io:80/v2*
 | [**UpdatePetWithForm**](PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data |
 | [**UploadFile**](PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image |
 | [**UploadFileWithRequiredFile**](PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required) |
+| [**UploadFiles**](PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images |
 
 <a id="addpet"></a>
 # **AddPet**
@@ -341,3 +342,38 @@ uploads an image (required)
 
 [[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
 
+<a id="uploadfiles"></a>
+# **UploadFiles**
+> ApiResponse UploadFiles (List<System.IO.Stream> files, long petId)
+
+uploads an images
+
+
+### Parameters
+
+| Name | Type | Description | Notes |
+|------|------|-------------|-------|
+| **files** | **List&lt;System.IO.Stream&gt;** |  |  |
+| **petId** | **long** | ID of pet to update |  |
+
+### Return type
+
+[**ApiResponse**](ApiResponse.md)
+
+### Authorization
+
+[petstore_auth](../README.md#petstore_auth)
+
+### HTTP request headers
+
+ - **Content-Type**: multipart/form-data
+ - **Accept**: application/json
+
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **200** | successful operation |  -  |
+
+[[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
+
diff --git a/samples/client/petstore/csharp/generichost/net4.8/Petstore/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs b/samples/client/petstore/csharp/generichost/net4.8/Petstore/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
index ce85f85778ef..6420b47bc8b4 100644
--- a/samples/client/petstore/csharp/generichost/net4.8/Petstore/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/net4.8/Petstore/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
@@ -196,7 +196,7 @@ public async Task TestEndpointParametersAsyncTest()
             string patternWithoutDelimiter = default;
             byte[] varByte = default;
             double varDouble = default;
-            Client.Option<System.IO.Stream> binary = default;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> binary = default;
             Client.Option<string> callback = default;
             Client.Option<DateTime> date = default;
             Client.Option<DateTime> dateTime = default;
diff --git a/samples/client/petstore/csharp/generichost/net4.8/Petstore/src/Org.OpenAPITools.Test/Api/PetApiTests.cs b/samples/client/petstore/csharp/generichost/net4.8/Petstore/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
index 215e88093797..e9b05337bb59 100644
--- a/samples/client/petstore/csharp/generichost/net4.8/Petstore/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/net4.8/Petstore/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
@@ -137,7 +137,7 @@ public async Task UploadFileAsyncTest()
         {
             long petId = default;
             Client.Option<string> additionalMetadata = default;
-            Client.Option<System.IO.Stream> file = default;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> file = default;
             var response = await _instance.UploadFileAsync(petId, additionalMetadata, file);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
@@ -150,11 +150,24 @@ public async Task UploadFileAsyncTest()
         public async Task UploadFileWithRequiredFileAsyncTest()
         {
             long petId = default;
-            System.IO.Stream requiredFile = default;
+            Org.OpenAPITools.Client.FileParameter requiredFile = default;
             Client.Option<string> additionalMetadata = default;
             var response = await _instance.UploadFileWithRequiredFileAsync(petId, requiredFile, additionalMetadata);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
         }
+
+        /// <summary>
+        /// Test UploadFiles
+        /// </summary>
+        [Fact (Skip = "not implemented")]
+        public async Task UploadFilesAsyncTest()
+        {
+            List<Org.OpenAPITools.Client.FileParameter> files = default;
+            long petId = default;
+            var response = await _instance.UploadFilesAsync(files, petId);
+            var model = response.Ok();
+            Assert.IsType<ApiResponse>(model);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/net4.8/Petstore/src/Org.OpenAPITools/Api/DefaultApi.cs b/samples/client/petstore/csharp/generichost/net4.8/Petstore/src/Org.OpenAPITools/Api/DefaultApi.cs
index 1bbf43279f7c..24a69b84527e 100644
--- a/samples/client/petstore/csharp/generichost/net4.8/Petstore/src/Org.OpenAPITools/Api/DefaultApi.cs
+++ b/samples/client/petstore/csharp/generichost/net4.8/Petstore/src/Org.OpenAPITools/Api/DefaultApi.cs
@@ -763,27 +763,19 @@ public async Task<IGetCountryApiResponse> GetCountryAsync(string country, System
                         ? "/country"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/country");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("country", ClientUtils.ParameterToString(country)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = new HttpMethod("POST");
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/net4.8/Petstore/src/Org.OpenAPITools/Api/FakeApi.cs b/samples/client/petstore/csharp/generichost/net4.8/Petstore/src/Org.OpenAPITools/Api/FakeApi.cs
index feec543b8c1f..a3a842305a6f 100644
--- a/samples/client/petstore/csharp/generichost/net4.8/Petstore/src/Org.OpenAPITools/Api/FakeApi.cs
+++ b/samples/client/petstore/csharp/generichost/net4.8/Petstore/src/Org.OpenAPITools/Api/FakeApi.cs
@@ -330,7 +330,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -354,7 +354,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// To test enum parameters
@@ -4071,7 +4071,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<System.IO.Stream> binary, ref Option<string> callback, ref Option<DateTime> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
+        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<Org.OpenAPITools.Client.FileParameter> binary, ref Option<string> callback, ref Option<DateTime> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
 
         /// <summary>
         /// Validates the request parameters
@@ -4083,7 +4083,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="password"></param>
         /// <param name="varString"></param>
         /// <returns></returns>
-        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<System.IO.Stream> binary, Option<string> callback, Option<string> password, Option<string> varString)
+        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<string> password, Option<string> varString)
         {
             if (patternWithoutDelimiter == null)
                 throw new ArgumentNullException(nameof(patternWithoutDelimiter));
@@ -4122,7 +4122,7 @@ private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLog = false;
             AfterTestEndpointParameters(ref suppressDefaultLog, apiResponseLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4149,7 +4149,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -4171,7 +4171,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorTestEndpointParameters(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4200,7 +4200,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트  Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -4221,7 +4221,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -4253,7 +4253,7 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDe
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -4272,14 +4272,8 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         ? "/fake"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("number", ClientUtils.ParameterToString(number)));
 
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("pattern_without_delimiter", ClientUtils.ParameterToString(patternWithoutDelimiter)));
@@ -4289,7 +4283,7 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("double", ClientUtils.ParameterToString(varDouble)));
 
                     if (binary.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(binary.Value));
+                        throw new NotSupportedException("File parameters cannot be sent with application/x-www-form-urlencoded. Change the operation's content type to multipart/form-data.");
 
                     if (callback.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("callback", ClientUtils.ParameterToString(callback.Value)));
@@ -4318,6 +4312,9 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                     if (varString.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("string", ClientUtils.ParameterToString(varString.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -4331,11 +4328,6 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = new HttpMethod("POST");
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -4628,29 +4620,23 @@ public async Task<ITestEnumParametersApiResponse> TestEnumParametersAsync(Option
                     if (enumHeaderStringArray.IsSet)
                         httpRequestMessageLocalVar.Headers.Add("enum_header_string_array", ClientUtils.ParameterToString(enumHeaderStringArray.Value));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (enumFormString.IsSet)
+                    if (enumFormString.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("enum_form_string", ClientUtils.ParameterToString(enumFormString.Value)));
 
                     if (enumFormStringArray.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("enum_form_string_array", ClientUtils.ParameterToString(enumFormStringArray.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = new HttpMethod("GET");
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -5536,29 +5522,21 @@ public async Task<ITestJsonFormDataApiResponse> TestJsonFormDataAsync(string par
                         ? "/fake/jsonFormData"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/jsonFormData");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("param", ClientUtils.ParameterToString(param)));
 
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("param2", ClientUtils.ParameterToString(param2)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = new HttpMethod("GET");
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/net4.8/Petstore/src/Org.OpenAPITools/Api/PetApi.cs b/samples/client/petstore/csharp/generichost/net4.8/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
index 7fe162b51bfb..9d04b53a95c5 100644
--- a/samples/client/petstore/csharp/generichost/net4.8/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
+++ b/samples/client/petstore/csharp/generichost/net4.8/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
@@ -216,7 +216,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image
@@ -229,7 +229,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -243,7 +243,7 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -256,7 +256,32 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        Task<IUploadFilesApiResponse> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
     }
 
     /// <summary>
@@ -415,6 +440,18 @@ public interface IUploadFileWithRequiredFileApiResponse : Org.OpenAPITools.Clien
         bool IsOk { get; }
     }
 
+    /// <summary>
+    /// The <see cref="IUploadFilesApiResponse"/>
+    /// </summary>
+    public interface IUploadFilesApiResponse : Org.OpenAPITools.Client.IApiResponse, IOk<Org.OpenAPITools.Model.ApiResponse>
+    {
+        /// <summary>
+        /// Returns true if the response is 200 Ok
+        /// </summary>
+        /// <returns></returns>
+        bool IsOk { get; }
+    }
+
     /// <summary>
     /// Represents a collection of functions to interact with the API endpoints
     /// </summary>
@@ -599,6 +636,26 @@ internal void ExecuteOnErrorUploadFileWithRequiredFile(Exception exception)
         {
             OnErrorUploadFileWithRequiredFile?.Invoke(this, new ExceptionEventArgs(exception));
         }
+
+        /// <summary>
+        /// The event raised after the server response
+        /// </summary>
+        public event EventHandler<ApiResponseEventArgs> OnUploadFiles;
+
+        /// <summary>
+        /// The event raised after an error querying the server
+        /// </summary>
+        public event EventHandler<ExceptionEventArgs> OnErrorUploadFiles;
+
+        internal void ExecuteOnUploadFiles(PetApi.UploadFilesApiResponse apiResponse)
+        {
+            OnUploadFiles?.Invoke(this, new ApiResponseEventArgs(apiResponse));
+        }
+
+        internal void ExecuteOnErrorUploadFiles(Exception exception)
+        {
+            OnErrorUploadFiles?.Invoke(this, new ExceptionEventArgs(exception));
+        }
     }
 
     /// <summary>
@@ -2326,18 +2383,17 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (name.IsSet)
+                    if (name.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("name", ClientUtils.ParameterToString(name.Value)));
 
                     if (status.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("status", ClientUtils.ParameterToString(status.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -2351,11 +2407,6 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = new HttpMethod("POST");
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -2455,7 +2506,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<System.IO.Stream> file);
+        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Validates the request parameters
@@ -2463,7 +2514,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
         /// <returns></returns>
-        private void ValidateUploadFile(Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void ValidateUploadFile(Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             if (additionalMetadata.IsSet && additionalMetadata.Value == null)
                 throw new ArgumentNullException(nameof(additionalMetadata));
@@ -2479,7 +2530,7 @@ private void ValidateUploadFile(Option<string> additionalMetadata, Option<System
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLog = false;
             AfterUploadFile(ref suppressDefaultLog, apiResponseLocalVar, petId, additionalMetadata, file);
@@ -2495,7 +2546,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2506,7 +2557,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, additionalMetadata, file);
@@ -2524,7 +2575,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// uploads an image 
@@ -2534,7 +2585,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2555,7 +2606,7 @@ public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, O
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2575,17 +2626,23 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImage");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (additionalMetadata.IsSet)
+                    if (additionalMetadata.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
 
                     if (file.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(file.Value));
+                    {
+                        var streamContentLocalVar = new StreamContent(file.Value.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "file", file.Value.FileName ?? "file");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -2600,11 +2657,6 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         "multipart/form-data"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json"
                     };
@@ -2744,7 +2796,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFileWithRequiredFile(ref long petId, ref System.IO.Stream requiredFile, ref Option<string> additionalMetadata);
+        partial void FormatUploadFileWithRequiredFile(ref long petId, ref Org.OpenAPITools.Client.FileParameter requiredFile, ref Option<string> additionalMetadata);
 
         /// <summary>
         /// Validates the request parameters
@@ -2752,7 +2804,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
         /// <returns></returns>
-        private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void ValidateUploadFileWithRequiredFile(Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             if (requiredFile == null)
                 throw new ArgumentNullException(nameof(requiredFile));
@@ -2768,7 +2820,7 @@ private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, O
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLog = false;
             AfterUploadFileWithRequiredFile(ref suppressDefaultLog, apiResponseLocalVar, petId, requiredFile, additionalMetadata);
@@ -2784,7 +2836,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2795,7 +2847,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFileWithRequiredFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, requiredFile, additionalMetadata);
@@ -2813,7 +2865,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// uploads an image (required) 
@@ -2823,7 +2875,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2844,7 +2896,7 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2864,17 +2916,23 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/{petId}/uploadImageWithRequiredFile");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    multipartContentLocalVar.Add(new StreamContent(requiredFile));
+                    {
+                        var streamContentLocalVar = new StreamContent(requiredFile.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "requiredFile", requiredFile.FileName ?? "requiredFile");
+                    }
 
                     if (additionalMetadata.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
 
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -2888,11 +2946,6 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         "multipart/form-data"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json",
                         "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
@@ -3032,5 +3085,282 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
 
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
+
+        partial void FormatUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files, ref long petId);
+
+        /// <summary>
+        /// Validates the request parameters
+        /// </summary>
+        /// <param name="files"></param>
+        /// <returns></returns>
+        private void ValidateUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files)
+        {
+            if (files == null)
+                throw new ArgumentNullException(nameof(files));
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void AfterUploadFilesDefaultImplementation(IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLog = false;
+            AfterUploadFiles(ref suppressDefaultLog, apiResponseLocalVar, files, petId);
+            if (!suppressDefaultLog)
+                Logger.LogInformation("{0,-9} | {1} | {2}", (apiResponseLocalVar.DownloadedAt - apiResponseLocalVar.RequestedAt).TotalSeconds, apiResponseLocalVar.StatusCode, apiResponseLocalVar.Path);
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="suppressDefaultLog"></param>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void AfterUploadFiles(ref bool suppressDefaultLog, IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// Logs exceptions that occur while retrieving the server response
+        /// </summary>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void OnErrorUploadFilesDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLogLocalVar = false;
+            OnErrorUploadFiles(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, files, petId);
+            if (!suppressDefaultLogLocalVar)
+                Logger.LogError(exceptionLocalVar, "An error occurred while sending the request to the server.");
+        }
+
+        /// <summary>
+        /// A partial method that gives developers a way to provide customized exception handling
+        /// </summary>
+        /// <param name="suppressDefaultLogLocalVar"></param>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void OnErrorUploadFiles(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            try
+            {
+                return await UploadFilesAsync(files, petId, cancellationToken).ConfigureAwait(false);
+            }
+            catch (Exception)
+            {
+                return null;
+            }
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            UriBuilder uriBuilderLocalVar = new UriBuilder();
+
+            try
+            {
+                ValidateUploadFiles(files);
+
+                FormatUploadFiles(files, ref petId);
+
+                using (HttpRequestMessage httpRequestMessageLocalVar = new HttpRequestMessage())
+                {
+                    uriBuilderLocalVar.Host = HttpClient.BaseAddress.Host;
+                    uriBuilderLocalVar.Port = HttpClient.BaseAddress.Port;
+                    uriBuilderLocalVar.Scheme = HttpClient.BaseAddress.Scheme;
+                    uriBuilderLocalVar.Path = HttpClient.BaseAddress.AbsolutePath == "/"
+                        ? "/pet/{petId}/uploadImages"
+                        : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImages");
+                    uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
+
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
+
+                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+
+                    List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
+
+                    foreach (Org.OpenAPITools.Client.FileParameter fileParameterLocalVar in files)
+                    {
+                        var streamContentLocalVar = new StreamContent(fileParameterLocalVar.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "files", fileParameterLocalVar.FileName ?? "files");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
+
+                    List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
+                    httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
+
+                    OAuthToken oauthTokenLocalVar1 = (OAuthToken) await OauthTokenProvider.GetAsync(cancellation: cancellationToken).ConfigureAwait(false);
+
+                    tokenBaseLocalVars.Add(oauthTokenLocalVar1);
+
+                    oauthTokenLocalVar1.UseInHeader(httpRequestMessageLocalVar, "");
+
+                    string[] contentTypes = new string[] {
+                        "multipart/form-data"
+                    };
+
+                    string[] acceptLocalVars = new string[] {
+                        "application/json"
+                    };
+
+                    IEnumerable<MediaTypeWithQualityHeaderValue> acceptHeaderValuesLocalVar = ClientUtils.SelectHeaderAcceptArray(acceptLocalVars);
+
+                    foreach (var acceptLocalVar in acceptHeaderValuesLocalVar)
+                        httpRequestMessageLocalVar.Headers.Accept.Add(acceptLocalVar);
+                    httpRequestMessageLocalVar.Method = new HttpMethod("POST");
+
+                    DateTime requestedAtLocalVar = DateTime.UtcNow;
+
+                    using (HttpResponseMessage httpResponseMessageLocalVar = await HttpClient.SendAsync(httpRequestMessageLocalVar, cancellationToken).ConfigureAwait(false))
+                    {
+                        ILogger<UploadFilesApiResponse> apiResponseLoggerLocalVar = LoggerFactory.CreateLogger<UploadFilesApiResponse>();
+                        UploadFilesApiResponse apiResponseLocalVar;
+
+                        switch ((int)httpResponseMessageLocalVar.StatusCode) {
+                            default: {
+                                string responseContentLocalVar = await httpResponseMessageLocalVar.Content.ReadAsStringAsync().ConfigureAwait(false);
+                                apiResponseLocalVar = new UploadFilesApiResponse(apiResponseLoggerLocalVar, httpRequestMessageLocalVar, httpResponseMessageLocalVar, responseContentLocalVar, "/pet/{petId}/uploadImages", requestedAtLocalVar, _jsonSerializerOptions);
+
+                                break;
+                            }
+                        }
+
+                        AfterUploadFilesDefaultImplementation(apiResponseLocalVar, files, petId);
+
+                        Events.ExecuteOnUploadFiles(apiResponseLocalVar);
+
+                        if (apiResponseLocalVar.StatusCode == (HttpStatusCode) 429)
+                            foreach(TokenBase tokenBaseLocalVar in tokenBaseLocalVars)
+                                tokenBaseLocalVar.BeginRateLimit();
+
+                        return apiResponseLocalVar;
+                    }
+                }
+            }
+            catch(Exception e)
+            {
+                OnErrorUploadFilesDefaultImplementation(e, "/pet/{petId}/uploadImages", uriBuilderLocalVar.Path, files, petId);
+                Events.ExecuteOnErrorUploadFiles(e);
+                throw;
+            }
+        }
+
+        /// <summary>
+        /// The <see cref="UploadFilesApiResponse"/>
+        /// </summary>
+        public partial class UploadFilesApiResponse : Org.OpenAPITools.Client.ApiResponse, IUploadFilesApiResponse
+        {
+            /// <summary>
+            /// The logger
+            /// </summary>
+            public ILogger<UploadFilesApiResponse> Logger { get; }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="rawContent"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, string rawContent, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, rawContent, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="contentStream"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, System.IO.Stream contentStream, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, contentStream, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            partial void OnCreated(global::System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage);
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public bool IsOk => 200 == (int)StatusCode;
+
+            /// <summary>
+            /// Deserializes the response if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public Org.OpenAPITools.Model.ApiResponse Ok()
+            {
+                // This logic may be modified with the AsModel.mustache template
+                return IsOk
+                    ? System.Text.Json.JsonSerializer.Deserialize<Org.OpenAPITools.Model.ApiResponse>(RawContent, _jsonSerializerOptions)
+                    : default;
+            }
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok and the deserialized response is not null
+            /// </summary>
+            /// <param name="result"></param>
+            /// <returns></returns>
+            public bool TryOk(out Org.OpenAPITools.Model.ApiResponse result)
+            {
+                result = null;
+
+                try
+                {
+                    result = Ok();
+                } catch (Exception e)
+                {
+                    OnDeserializationErrorDefaultImplementation(e, (HttpStatusCode)200);
+                }
+
+                return result != null;
+            }
+
+            private void OnDeserializationErrorDefaultImplementation(Exception exception, HttpStatusCode httpStatusCode)
+            {
+                bool suppressDefaultLog = false;
+                OnDeserializationError(ref suppressDefaultLog, exception, httpStatusCode);
+                if (!suppressDefaultLog)
+                    Logger.LogError(exception, "An error occurred while deserializing the {code} response.", httpStatusCode);
+            }
+
+            partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/net4.8/Petstore/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net4.8/Petstore/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..6150dbcf4774
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net4.8/Petstore/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,40 @@
+// <auto-generated>
+/*
+ * OpenAPI Petstore
+ *
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net4.8/UseDateTimeForDate/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net4.8/UseDateTimeForDate/.openapi-generator/FILES
index 5abbcf46f35c..e28da391730f 100644
--- a/samples/client/petstore/csharp/generichost/net4.8/UseDateTimeForDate/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net4.8/UseDateTimeForDate/.openapi-generator/FILES
@@ -21,6 +21,7 @@ src/Org.OpenAPITools/Client/CookieContainer.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/JsonSerializerOptionsProvider.cs
 src/Org.OpenAPITools/Client/Option.cs
diff --git a/samples/client/petstore/csharp/generichost/net4.8/UseDateTimeForDate/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net4.8/UseDateTimeForDate/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..253a70bc8053
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net4.8/UseDateTimeForDate/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,40 @@
+// <auto-generated>
+/*
+ * OpenAPI Dates
+ *
+ * Thic spec contains endpoints with dates in different formats
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net8/AllOf/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net8/AllOf/.openapi-generator/FILES
index b9ab612bd8b5..46a8286dea29 100644
--- a/samples/client/petstore/csharp/generichost/net8/AllOf/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net8/AllOf/.openapi-generator/FILES
@@ -25,6 +25,7 @@ src/Org.OpenAPITools/Client/DateOnlyNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/JsonSerializerOptionsProvider.cs
 src/Org.OpenAPITools/Client/Option.cs
diff --git a/samples/client/petstore/csharp/generichost/net8/AllOf/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net8/AllOf/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..1913a3a0f2d9
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net8/AllOf/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,42 @@
+// <auto-generated>
+/*
+ * Example
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+#nullable enable
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string? FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string? fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net8/AnyOf/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net8/AnyOf/.openapi-generator/FILES
index dc42a5d47091..072cc8408121 100644
--- a/samples/client/petstore/csharp/generichost/net8/AnyOf/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net8/AnyOf/.openapi-generator/FILES
@@ -25,6 +25,7 @@ src/Org.OpenAPITools/Client/DateOnlyNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/JsonSerializerOptionsProvider.cs
 src/Org.OpenAPITools/Client/Option.cs
diff --git a/samples/client/petstore/csharp/generichost/net8/AnyOf/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net8/AnyOf/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..e629f4afdaec
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net8/AnyOf/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,42 @@
+// <auto-generated>
+/*
+ * fruity
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * The version of the OpenAPI document: 0.0.1
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+#nullable enable
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string? FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string? fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net8/AnyOfNoCompare/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net8/AnyOfNoCompare/.openapi-generator/FILES
index dc42a5d47091..072cc8408121 100644
--- a/samples/client/petstore/csharp/generichost/net8/AnyOfNoCompare/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net8/AnyOfNoCompare/.openapi-generator/FILES
@@ -25,6 +25,7 @@ src/Org.OpenAPITools/Client/DateOnlyNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/JsonSerializerOptionsProvider.cs
 src/Org.OpenAPITools/Client/Option.cs
diff --git a/samples/client/petstore/csharp/generichost/net8/AnyOfNoCompare/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net8/AnyOfNoCompare/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..e629f4afdaec
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net8/AnyOfNoCompare/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,42 @@
+// <auto-generated>
+/*
+ * fruity
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * The version of the OpenAPI document: 0.0.1
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+#nullable enable
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string? FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string? fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net8/FormModels/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net8/FormModels/.openapi-generator/FILES
index a9823b3075fd..737d53400248 100644
--- a/samples/client/petstore/csharp/generichost/net8/FormModels/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net8/FormModels/.openapi-generator/FILES
@@ -165,6 +165,7 @@ src/Org.OpenAPITools/Client/DateOnlyNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningToken.cs
diff --git a/samples/client/petstore/csharp/generichost/net8/FormModels/api/openapi.yaml b/samples/client/petstore/csharp/generichost/net8/FormModels/api/openapi.yaml
index a9ab8dd51c13..7017affc0b9c 100644
--- a/samples/client/petstore/csharp/generichost/net8/FormModels/api/openapi.yaml
+++ b/samples/client/petstore/csharp/generichost/net8/FormModels/api/openapi.yaml
@@ -326,6 +326,40 @@ paths:
       summary: uploads an image
       tags:
       - pet
+  /pet/{petId}/uploadImages:
+    post:
+      description: ""
+      operationId: uploadFiles
+      parameters:
+      - description: ID of pet to update
+        explode: false
+        in: path
+        name: petId
+        required: true
+        schema:
+          format: int64
+          type: integer
+        style: simple
+      requestBody:
+        content:
+          multipart/form-data:
+            schema:
+              $ref: "#/components/schemas/uploadFiles_request"
+        required: true
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ApiResponse"
+          description: successful operation
+      security:
+      - petstore_auth:
+        - write:pets
+        - read:pets
+      summary: uploads an images
+      tags:
+      - pet
   /store/inventory:
     get:
       description: Returns a map of status codes to quantities
@@ -2748,6 +2782,16 @@ components:
           format: binary
           type: string
       type: object
+    uploadFiles_request:
+      properties:
+        files:
+          items:
+            format: binary
+            type: string
+          type: array
+      required:
+      - files
+      type: object
     testEnumParameters_request_enum_form_string_array_inner:
       default: $
       enum:
diff --git a/samples/client/petstore/csharp/generichost/net8/FormModels/docs/apis/PetApi.md b/samples/client/petstore/csharp/generichost/net8/FormModels/docs/apis/PetApi.md
index e32c1e31e089..59d4ef8e6df0 100644
--- a/samples/client/petstore/csharp/generichost/net8/FormModels/docs/apis/PetApi.md
+++ b/samples/client/petstore/csharp/generichost/net8/FormModels/docs/apis/PetApi.md
@@ -13,6 +13,7 @@ All URIs are relative to *http://petstore.swagger.io:80/v2*
 | [**UpdatePetWithForm**](PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data |
 | [**UploadFile**](PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image |
 | [**UploadFileWithRequiredFile**](PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required) |
+| [**UploadFiles**](PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images |
 
 <a id="addpet"></a>
 # **AddPet**
@@ -341,3 +342,38 @@ uploads an image (required)
 
 [[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
 
+<a id="uploadfiles"></a>
+# **UploadFiles**
+> ApiResponse UploadFiles (List<System.IO.Stream> files, long petId)
+
+uploads an images
+
+
+### Parameters
+
+| Name | Type | Description | Notes |
+|------|------|-------------|-------|
+| **files** | **List&lt;System.IO.Stream&gt;** |  |  |
+| **petId** | **long** | ID of pet to update |  |
+
+### Return type
+
+[**ApiResponse**](ApiResponse.md)
+
+### Authorization
+
+[petstore_auth](../README.md#petstore_auth)
+
+### HTTP request headers
+
+ - **Content-Type**: multipart/form-data
+ - **Accept**: application/json
+
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **200** | successful operation |  -  |
+
+[[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
+
diff --git a/samples/client/petstore/csharp/generichost/net8/FormModels/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs b/samples/client/petstore/csharp/generichost/net8/FormModels/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
index 495d785314c5..1924842cdbef 100644
--- a/samples/client/petstore/csharp/generichost/net8/FormModels/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/net8/FormModels/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
@@ -196,7 +196,7 @@ public async Task TestEndpointParametersAsyncTest()
             string patternWithoutDelimiter = default;
             byte[] varByte = default;
             double varDouble = default;
-            Client.Option<System.IO.Stream> binary = default;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> binary = default;
             Client.Option<string> callback = default;
             Client.Option<DateOnly> date = default;
             Client.Option<DateTime> dateTime = default;
diff --git a/samples/client/petstore/csharp/generichost/net8/FormModels/src/Org.OpenAPITools.Test/Api/PetApiTests.cs b/samples/client/petstore/csharp/generichost/net8/FormModels/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
index 1f1d7f6c4576..a4aa8f3e245d 100644
--- a/samples/client/petstore/csharp/generichost/net8/FormModels/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/net8/FormModels/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
@@ -137,7 +137,7 @@ public async Task UploadFileAsyncTest()
         {
             long petId = default;
             Client.Option<string> additionalMetadata = default;
-            Client.Option<System.IO.Stream> file = default;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> file = default;
             var response = await _instance.UploadFileAsync(petId, additionalMetadata, file);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
@@ -150,11 +150,24 @@ public async Task UploadFileAsyncTest()
         public async Task UploadFileWithRequiredFileAsyncTest()
         {
             long petId = default;
-            System.IO.Stream requiredFile = default;
+            Org.OpenAPITools.Client.FileParameter requiredFile = default;
             Client.Option<string> additionalMetadata = default;
             var response = await _instance.UploadFileWithRequiredFileAsync(petId, requiredFile, additionalMetadata);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
         }
+
+        /// <summary>
+        /// Test UploadFiles
+        /// </summary>
+        [Fact (Skip = "not implemented")]
+        public async Task UploadFilesAsyncTest()
+        {
+            List<Org.OpenAPITools.Client.FileParameter> files = default;
+            long petId = default;
+            var response = await _instance.UploadFilesAsync(files, petId);
+            var model = response.Ok();
+            Assert.IsType<ApiResponse>(model);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/net8/FormModels/src/Org.OpenAPITools/Api/DefaultApi.cs b/samples/client/petstore/csharp/generichost/net8/FormModels/src/Org.OpenAPITools/Api/DefaultApi.cs
index 3c26a27185e6..44d52e7e1090 100644
--- a/samples/client/petstore/csharp/generichost/net8/FormModels/src/Org.OpenAPITools/Api/DefaultApi.cs
+++ b/samples/client/petstore/csharp/generichost/net8/FormModels/src/Org.OpenAPITools/Api/DefaultApi.cs
@@ -764,27 +764,19 @@ public async Task<IGetCountryApiResponse> GetCountryAsync(string country, System
                         ? "/country"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/country");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("country", ClientUtils.ParameterToString(country)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/net8/FormModels/src/Org.OpenAPITools/Api/FakeApi.cs b/samples/client/petstore/csharp/generichost/net8/FormModels/src/Org.OpenAPITools/Api/FakeApi.cs
index 2a332dbf1eb9..0070617289e6 100644
--- a/samples/client/petstore/csharp/generichost/net8/FormModels/src/Org.OpenAPITools/Api/FakeApi.cs
+++ b/samples/client/petstore/csharp/generichost/net8/FormModels/src/Org.OpenAPITools/Api/FakeApi.cs
@@ -330,7 +330,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -354,7 +354,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// To test enum parameters
@@ -4080,7 +4080,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<System.IO.Stream> binary, ref Option<string> callback, ref Option<DateOnly> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
+        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<Org.OpenAPITools.Client.FileParameter> binary, ref Option<string> callback, ref Option<DateOnly> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
 
         /// <summary>
         /// Validates the request parameters
@@ -4092,7 +4092,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="password"></param>
         /// <param name="varString"></param>
         /// <returns></returns>
-        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<System.IO.Stream> binary, Option<string> callback, Option<string> password, Option<string> varString)
+        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<string> password, Option<string> varString)
         {
             if (patternWithoutDelimiter == null)
                 throw new ArgumentNullException(nameof(patternWithoutDelimiter));
@@ -4131,7 +4131,7 @@ private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLog = false;
             AfterTestEndpointParameters(ref suppressDefaultLog, apiResponseLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4158,7 +4158,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -4180,7 +4180,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorTestEndpointParameters(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4209,7 +4209,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트  Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -4230,7 +4230,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -4262,7 +4262,7 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDe
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -4281,14 +4281,8 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         ? "/fake"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("number", ClientUtils.ParameterToString(number)));
 
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("pattern_without_delimiter", ClientUtils.ParameterToString(patternWithoutDelimiter)));
@@ -4298,7 +4292,7 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("double", ClientUtils.ParameterToString(varDouble)));
 
                     if (binary.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(binary.Value));
+                        throw new NotSupportedException("File parameters cannot be sent with application/x-www-form-urlencoded. Change the operation's content type to multipart/form-data.");
 
                     if (callback.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("callback", ClientUtils.ParameterToString(callback.Value)));
@@ -4327,6 +4321,9 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                     if (varString.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("string", ClientUtils.ParameterToString(varString.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -4340,11 +4337,6 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -4625,29 +4617,23 @@ public async Task<ITestEnumParametersApiResponse> TestEnumParametersAsync(Option
                     if (enumHeaderStringArray.IsSet)
                         httpRequestMessageLocalVar.Headers.Add("enum_header_string_array", ClientUtils.ParameterToString(enumHeaderStringArray.Value));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (enumFormString.IsSet)
+                    if (enumFormString.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("enum_form_string", ClientUtils.ParameterToString(enumFormString.Value)));
 
                     if (enumFormStringArray.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("enum_form_string_array", ClientUtils.ParameterToString(enumFormStringArray.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Get;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -5534,29 +5520,21 @@ public async Task<ITestJsonFormDataApiResponse> TestJsonFormDataAsync(string par
                         ? "/fake/jsonFormData"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/jsonFormData");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("param", ClientUtils.ParameterToString(param)));
 
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("param2", ClientUtils.ParameterToString(param2)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Get;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/net8/FormModels/src/Org.OpenAPITools/Api/PetApi.cs b/samples/client/petstore/csharp/generichost/net8/FormModels/src/Org.OpenAPITools/Api/PetApi.cs
index d07d16c30828..fd403446d9a6 100644
--- a/samples/client/petstore/csharp/generichost/net8/FormModels/src/Org.OpenAPITools/Api/PetApi.cs
+++ b/samples/client/petstore/csharp/generichost/net8/FormModels/src/Org.OpenAPITools/Api/PetApi.cs
@@ -216,7 +216,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image
@@ -229,7 +229,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -243,7 +243,7 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -256,7 +256,32 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        Task<IUploadFilesApiResponse> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
     }
 
     /// <summary>
@@ -415,6 +440,18 @@ public interface IUploadFileWithRequiredFileApiResponse : Org.OpenAPITools.Clien
         bool IsOk { get; }
     }
 
+    /// <summary>
+    /// The <see cref="IUploadFilesApiResponse"/>
+    /// </summary>
+    public interface IUploadFilesApiResponse : Org.OpenAPITools.Client.IApiResponse, IOk<Org.OpenAPITools.Model.ApiResponse>
+    {
+        /// <summary>
+        /// Returns true if the response is 200 Ok
+        /// </summary>
+        /// <returns></returns>
+        bool IsOk { get; }
+    }
+
     /// <summary>
     /// Represents a collection of functions to interact with the API endpoints
     /// </summary>
@@ -599,6 +636,26 @@ internal void ExecuteOnErrorUploadFileWithRequiredFile(Exception exception)
         {
             OnErrorUploadFileWithRequiredFile?.Invoke(this, new ExceptionEventArgs(exception));
         }
+
+        /// <summary>
+        /// The event raised after the server response
+        /// </summary>
+        public event EventHandler<ApiResponseEventArgs> OnUploadFiles;
+
+        /// <summary>
+        /// The event raised after an error querying the server
+        /// </summary>
+        public event EventHandler<ExceptionEventArgs> OnErrorUploadFiles;
+
+        internal void ExecuteOnUploadFiles(PetApi.UploadFilesApiResponse apiResponse)
+        {
+            OnUploadFiles?.Invoke(this, new ApiResponseEventArgs(apiResponse));
+        }
+
+        internal void ExecuteOnErrorUploadFiles(Exception exception)
+        {
+            OnErrorUploadFiles?.Invoke(this, new ExceptionEventArgs(exception));
+        }
     }
 
     /// <summary>
@@ -2330,18 +2387,17 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (name.IsSet)
+                    if (name.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("name", ClientUtils.ParameterToString(name.Value)));
 
                     if (status.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("status", ClientUtils.ParameterToString(status.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -2355,11 +2411,6 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -2459,7 +2510,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<System.IO.Stream> file);
+        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Validates the request parameters
@@ -2467,7 +2518,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
         /// <returns></returns>
-        private void ValidateUploadFile(Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void ValidateUploadFile(Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             if (additionalMetadata.IsSet && additionalMetadata.Value == null)
                 throw new ArgumentNullException(nameof(additionalMetadata));
@@ -2483,7 +2534,7 @@ private void ValidateUploadFile(Option<string> additionalMetadata, Option<System
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLog = false;
             AfterUploadFile(ref suppressDefaultLog, apiResponseLocalVar, petId, additionalMetadata, file);
@@ -2499,7 +2550,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2510,7 +2561,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, additionalMetadata, file);
@@ -2528,7 +2579,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// uploads an image 
@@ -2538,7 +2589,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2559,7 +2610,7 @@ public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, O
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2579,17 +2630,23 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImage");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (additionalMetadata.IsSet)
+                    if (additionalMetadata.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
 
                     if (file.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(file.Value));
+                    {
+                        var streamContentLocalVar = new StreamContent(file.Value.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "file", file.Value.FileName ?? "file");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -2604,11 +2661,6 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         "multipart/form-data"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json"
                     };
@@ -2749,7 +2801,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFileWithRequiredFile(ref long petId, ref System.IO.Stream requiredFile, ref Option<string> additionalMetadata);
+        partial void FormatUploadFileWithRequiredFile(ref long petId, ref Org.OpenAPITools.Client.FileParameter requiredFile, ref Option<string> additionalMetadata);
 
         /// <summary>
         /// Validates the request parameters
@@ -2757,7 +2809,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
         /// <returns></returns>
-        private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void ValidateUploadFileWithRequiredFile(Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             if (requiredFile == null)
                 throw new ArgumentNullException(nameof(requiredFile));
@@ -2773,7 +2825,7 @@ private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, O
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLog = false;
             AfterUploadFileWithRequiredFile(ref suppressDefaultLog, apiResponseLocalVar, petId, requiredFile, additionalMetadata);
@@ -2789,7 +2841,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2800,7 +2852,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFileWithRequiredFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, requiredFile, additionalMetadata);
@@ -2818,7 +2870,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// uploads an image (required) 
@@ -2828,7 +2880,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2849,7 +2901,7 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2869,17 +2921,23 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/{petId}/uploadImageWithRequiredFile");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    multipartContentLocalVar.Add(new StreamContent(requiredFile));
+                    {
+                        var streamContentLocalVar = new StreamContent(requiredFile.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "requiredFile", requiredFile.FileName ?? "requiredFile");
+                    }
 
                     if (additionalMetadata.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
 
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -2893,11 +2951,6 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         "multipart/form-data"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json",
                         "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
@@ -3038,5 +3091,283 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
 
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
+
+        partial void FormatUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files, ref long petId);
+
+        /// <summary>
+        /// Validates the request parameters
+        /// </summary>
+        /// <param name="files"></param>
+        /// <returns></returns>
+        private void ValidateUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files)
+        {
+            if (files == null)
+                throw new ArgumentNullException(nameof(files));
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void AfterUploadFilesDefaultImplementation(IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLog = false;
+            AfterUploadFiles(ref suppressDefaultLog, apiResponseLocalVar, files, petId);
+            if (!suppressDefaultLog)
+                Logger.LogInformation("{0,-9} | {1} | {2}", (apiResponseLocalVar.DownloadedAt - apiResponseLocalVar.RequestedAt).TotalSeconds, apiResponseLocalVar.StatusCode, apiResponseLocalVar.Path);
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="suppressDefaultLog"></param>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void AfterUploadFiles(ref bool suppressDefaultLog, IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// Logs exceptions that occur while retrieving the server response
+        /// </summary>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void OnErrorUploadFilesDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLogLocalVar = false;
+            OnErrorUploadFiles(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, files, petId);
+            if (!suppressDefaultLogLocalVar)
+                Logger.LogError(exceptionLocalVar, "An error occurred while sending the request to the server.");
+        }
+
+        /// <summary>
+        /// A partial method that gives developers a way to provide customized exception handling
+        /// </summary>
+        /// <param name="suppressDefaultLogLocalVar"></param>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void OnErrorUploadFiles(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            try
+            {
+                return await UploadFilesAsync(files, petId, cancellationToken).ConfigureAwait(false);
+            }
+            catch (Exception)
+            {
+                return null;
+            }
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            UriBuilder uriBuilderLocalVar = new UriBuilder();
+
+            try
+            {
+                ValidateUploadFiles(files);
+
+                FormatUploadFiles(files, ref petId);
+
+                using (HttpRequestMessage httpRequestMessageLocalVar = new HttpRequestMessage())
+                {
+                    uriBuilderLocalVar.Host = HttpClient.BaseAddress.Host;
+                    uriBuilderLocalVar.Port = HttpClient.BaseAddress.Port;
+                    uriBuilderLocalVar.Scheme = HttpClient.BaseAddress.Scheme;
+                    uriBuilderLocalVar.Path = HttpClient.BaseAddress.AbsolutePath == "/"
+                        ? "/pet/{petId}/uploadImages"
+                        : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImages");
+                    uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
+
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
+
+                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+
+                    List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
+
+                    foreach (Org.OpenAPITools.Client.FileParameter fileParameterLocalVar in files)
+                    {
+                        var streamContentLocalVar = new StreamContent(fileParameterLocalVar.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "files", fileParameterLocalVar.FileName ?? "files");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
+
+                    List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
+                    httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
+
+                    OAuthToken oauthTokenLocalVar1 = (OAuthToken) await OauthTokenProvider.GetAsync(cancellation: cancellationToken).ConfigureAwait(false);
+
+                    tokenBaseLocalVars.Add(oauthTokenLocalVar1);
+
+                    oauthTokenLocalVar1.UseInHeader(httpRequestMessageLocalVar, "");
+
+                    string[] contentTypes = new string[] {
+                        "multipart/form-data"
+                    };
+
+                    string[] acceptLocalVars = new string[] {
+                        "application/json"
+                    };
+
+                    IEnumerable<MediaTypeWithQualityHeaderValue> acceptHeaderValuesLocalVar = ClientUtils.SelectHeaderAcceptArray(acceptLocalVars);
+
+                    foreach (var acceptLocalVar in acceptHeaderValuesLocalVar)
+                        httpRequestMessageLocalVar.Headers.Accept.Add(acceptLocalVar);
+
+                    httpRequestMessageLocalVar.Method = HttpMethod.Post;
+
+                    DateTime requestedAtLocalVar = DateTime.UtcNow;
+
+                    using (HttpResponseMessage httpResponseMessageLocalVar = await HttpClient.SendAsync(httpRequestMessageLocalVar, cancellationToken).ConfigureAwait(false))
+                    {
+                        ILogger<UploadFilesApiResponse> apiResponseLoggerLocalVar = LoggerFactory.CreateLogger<UploadFilesApiResponse>();
+                        UploadFilesApiResponse apiResponseLocalVar;
+
+                        switch ((int)httpResponseMessageLocalVar.StatusCode) {
+                            default: {
+                                string responseContentLocalVar = await httpResponseMessageLocalVar.Content.ReadAsStringAsync(cancellationToken).ConfigureAwait(false);
+                                apiResponseLocalVar = new(apiResponseLoggerLocalVar, httpRequestMessageLocalVar, httpResponseMessageLocalVar, responseContentLocalVar, "/pet/{petId}/uploadImages", requestedAtLocalVar, _jsonSerializerOptions);
+
+                                break;
+                            }
+                        }
+
+                        AfterUploadFilesDefaultImplementation(apiResponseLocalVar, files, petId);
+
+                        Events.ExecuteOnUploadFiles(apiResponseLocalVar);
+
+                        if (apiResponseLocalVar.StatusCode == (HttpStatusCode) 429)
+                            foreach(TokenBase tokenBaseLocalVar in tokenBaseLocalVars)
+                                tokenBaseLocalVar.BeginRateLimit();
+
+                        return apiResponseLocalVar;
+                    }
+                }
+            }
+            catch(Exception e)
+            {
+                OnErrorUploadFilesDefaultImplementation(e, "/pet/{petId}/uploadImages", uriBuilderLocalVar.Path, files, petId);
+                Events.ExecuteOnErrorUploadFiles(e);
+                throw;
+            }
+        }
+
+        /// <summary>
+        /// The <see cref="UploadFilesApiResponse"/>
+        /// </summary>
+        public partial class UploadFilesApiResponse : Org.OpenAPITools.Client.ApiResponse, IUploadFilesApiResponse
+        {
+            /// <summary>
+            /// The logger
+            /// </summary>
+            public ILogger<UploadFilesApiResponse> Logger { get; }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="rawContent"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, string rawContent, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, rawContent, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="contentStream"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, System.IO.Stream contentStream, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, contentStream, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            partial void OnCreated(global::System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage);
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public bool IsOk => 200 == (int)StatusCode;
+
+            /// <summary>
+            /// Deserializes the response if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public Org.OpenAPITools.Model.ApiResponse Ok()
+            {
+                // This logic may be modified with the AsModel.mustache template
+                return IsOk
+                    ? System.Text.Json.JsonSerializer.Deserialize<Org.OpenAPITools.Model.ApiResponse>(RawContent, _jsonSerializerOptions)
+                    : null;
+            }
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok and the deserialized response is not null
+            /// </summary>
+            /// <param name="result"></param>
+            /// <returns></returns>
+            public bool TryOk([NotNullWhen(true)]out Org.OpenAPITools.Model.ApiResponse result)
+            {
+                result = null;
+
+                try
+                {
+                    result = Ok();
+                } catch (Exception e)
+                {
+                    OnDeserializationErrorDefaultImplementation(e, (HttpStatusCode)200);
+                }
+
+                return result != null;
+            }
+
+            private void OnDeserializationErrorDefaultImplementation(Exception exception, HttpStatusCode httpStatusCode)
+            {
+                bool suppressDefaultLog = false;
+                OnDeserializationError(ref suppressDefaultLog, exception, httpStatusCode);
+                if (!suppressDefaultLog)
+                    Logger.LogError(exception, "An error occurred while deserializing the {code} response.", httpStatusCode);
+            }
+
+            partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/net8/FormModels/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net8/FormModels/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..6150dbcf4774
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net8/FormModels/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,40 @@
+// <auto-generated>
+/*
+ * OpenAPI Petstore
+ *
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net8/ManualPetstoreTests/OpenAPIClient-generichost-manual-tests/MultipartContentTypeTests.cs b/samples/client/petstore/csharp/generichost/net8/ManualPetstoreTests/OpenAPIClient-generichost-manual-tests/MultipartContentTypeTests.cs
new file mode 100644
index 000000000000..11b7f610913a
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net8/ManualPetstoreTests/OpenAPIClient-generichost-manual-tests/MultipartContentTypeTests.cs
@@ -0,0 +1,302 @@
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+using Org.OpenAPITools.Api;
+using Org.OpenAPITools.Client;
+using Org.OpenAPITools.Extensions;
+using System.Net;
+using System.Net.Http.Headers;
+
+namespace OpenAPIClient_generichost_manual_tests
+{
+    /// <summary>
+    /// Tests that multipart/form-data requests preserve the boundary in their Content-Type header.
+    /// Regression test for https://github.com/OpenAPITools/openapi-generator/issues/21384
+    /// </summary>
+    [TestClass]
+    public sealed class MultipartContentTypeTests
+    {
+        /// <summary>
+        /// Captures the outgoing HttpRequestMessage and returns a minimal fake response,
+        /// so tests can inspect what the generated client actually sends without a real server.
+        /// </summary>
+        private sealed class CapturingHandler : HttpMessageHandler
+        {
+            public HttpRequestMessage? CapturedRequest { get; private set; }
+            public string? CapturedContentType { get; private set; }
+            public string? CapturedBody { get; private set; }
+
+            protected override async Task<HttpResponseMessage> SendAsync(
+                HttpRequestMessage request, CancellationToken cancellationToken)
+            {
+                CapturedRequest = request;
+                CapturedContentType = request.Content?.Headers.ContentType?.ToString();
+                CapturedBody = request.Content is not null
+                    ? await request.Content.ReadAsStringAsync(cancellationToken)
+                    : null;
+
+                var response = new HttpResponseMessage(HttpStatusCode.OK)
+                {
+                    Content = new StringContent(
+                        """{"code":200,"type":"ok","message":"ok"}""",
+                        System.Text.Encoding.UTF8,
+                        "application/json")
+                };
+
+                return response;
+            }
+        }
+
+        private IHost _host = null!;
+        private CapturingHandler _capturingHandler = null!;
+
+        [TestInitialize]
+        public void Setup()
+        {
+            _capturingHandler = new CapturingHandler();
+
+            IHostBuilder hostBuilder = Host.CreateDefaultBuilder(Array.Empty<string>())
+                .ConfigureApi((context, services, options) =>
+                {
+                    options.AddTokens(new ApiKeyToken("test-key", ClientUtils.ApiKeyHeader.Api_key, timeout: TimeSpan.FromSeconds(1)));
+                    options.AddTokens(new BearerToken("test-bearer", timeout: TimeSpan.FromSeconds(1)));
+                    options.AddTokens(new BasicToken("user", "pass", timeout: TimeSpan.FromSeconds(1)));
+                    options.AddTokens(new OAuthToken("test-oauth", timeout: TimeSpan.FromSeconds(1)));
+
+                    HttpSigningConfiguration signingConfig = new("<keyId>", "<keyFilePath>", null,
+                        new List<string>(), System.Security.Cryptography.HashAlgorithmName.SHA256, "<algo>", 0);
+                    options.AddTokens(new HttpSignatureToken(signingConfig, timeout: TimeSpan.FromSeconds(1)));
+
+                    options.AddApiHttpClients(
+                        client: c => c.BaseAddress = new Uri("http://localhost/"),
+                        builder: b => b.ConfigurePrimaryHttpMessageHandler(() => _capturingHandler));
+                });
+
+            _host = hostBuilder.Build();
+        }
+
+        [TestCleanup]
+        public void Cleanup()
+        {
+            _host.Dispose();
+            _capturingHandler.Dispose();
+        }
+
+        [TestMethod]
+        public async Task UploadFile_SingleOptionalFile_ContentTypeHasBoundary()
+        {
+            var petApi = _host.Services.GetRequiredService<IPetApi>();
+            using var stream = new MemoryStream(new byte[] { 1, 2, 3 });
+
+            await petApi.UploadFileAsync(petId: 1, file: new Option<FileParameter>(new FileParameter(stream)));
+
+            Assert.IsNotNull(_capturingHandler.CapturedContentType,
+                "Content-Type header should not be null for a multipart/form-data request.");
+            StringAssert.Contains(_capturingHandler.CapturedContentType, "multipart/form-data",
+                "Content-Type should be multipart/form-data.");
+            StringAssert.Contains(_capturingHandler.CapturedContentType, "boundary=",
+                "Content-Type must include a boundary parameter so the server can parse the body.");
+        }
+
+        [TestMethod]
+        public async Task UploadFile_SingleOptionalFile_BodyContainsFileWithCorrectFieldName()
+        {
+            var petApi = _host.Services.GetRequiredService<IPetApi>();
+            using var stream = new MemoryStream(new byte[] { 1, 2, 3 });
+
+            await petApi.UploadFileAsync(petId: 1, file: new Option<FileParameter>(new FileParameter(stream)));
+
+            Assert.IsNotNull(_capturingHandler.CapturedBody, "Body should not be null.");
+            // .NET's MultipartFormDataContent writes unquoted names: name=file (valid per RFC 7578)
+            StringAssert.Contains(_capturingHandler.CapturedBody, "name=file",
+                "Multipart part should use the field name 'file' as defined in the spec.");
+        }
+
+        [TestMethod]
+        public async Task UploadFiles_MultipleRequiredFiles_ContentTypeHasBoundary()
+        {
+            var petApi = _host.Services.GetRequiredService<IPetApi>();
+            using var stream1 = new MemoryStream(new byte[] { 1, 2, 3 });
+            using var stream2 = new MemoryStream(new byte[] { 4, 5, 6 });
+
+            await petApi.UploadFilesAsync(
+                files: new List<FileParameter> { new FileParameter(stream1), new FileParameter(stream2) },
+                petId: 1);
+
+            Assert.IsNotNull(_capturingHandler.CapturedContentType,
+                "Content-Type header should not be null for a multipart/form-data request.");
+            StringAssert.Contains(_capturingHandler.CapturedContentType, "multipart/form-data",
+                "Content-Type should be multipart/form-data.");
+            StringAssert.Contains(_capturingHandler.CapturedContentType, "boundary=",
+                "Content-Type must include a boundary parameter so the server can parse the body.");
+        }
+
+        [TestMethod]
+        public async Task UploadFiles_MultipleRequiredFiles_BodyContainsBothFilesWithCorrectFieldName()
+        {
+            var petApi = _host.Services.GetRequiredService<IPetApi>();
+            using var stream1 = new MemoryStream(new byte[] { 10, 20, 30 });
+            using var stream2 = new MemoryStream(new byte[] { 40, 50, 60 });
+
+            await petApi.UploadFilesAsync(
+                files: new List<FileParameter> { new FileParameter(stream1), new FileParameter(stream2) },
+                petId: 1);
+
+            Assert.IsNotNull(_capturingHandler.CapturedBody, "Body should not be null.");
+
+            // Count Content-Disposition headers for the "files" field. Each stream must appear as
+            // its own named part. Matching the full header prefix avoids false positives from
+            // "filename=files" which also contains "name=files" as a substring.
+            var parts = _capturingHandler.CapturedBody!.Split("Content-Disposition: form-data; name=files");
+            Assert.AreEqual(3, parts.Length,
+                "Body should contain exactly two parts named 'files' (one per stream), " +
+                $"but found {parts.Length - 1}. Body:\n{_capturingHandler.CapturedBody}");
+        }
+
+        /// <summary>
+        /// Covers issue #21384: multipart/form-data with only text form fields (no file)
+        /// must still include the boundary in Content-Type so the server can parse the body.
+        /// Uses UploadFileAsync with only the optional additionalMetadata text field, no file.
+        /// </summary>
+        [TestMethod]
+        public async Task UploadFile_TextFieldOnly_NoFile_ContentTypeHasBoundary()
+        {
+            var petApi = _host.Services.GetRequiredService<IPetApi>();
+
+            await petApi.UploadFileAsync(
+                petId: 1,
+                additionalMetadata: new Option<string>("some metadata"));
+
+            Assert.IsNotNull(_capturingHandler.CapturedContentType,
+                "Content-Type header should not be null for a multipart/form-data request.");
+            StringAssert.Contains(_capturingHandler.CapturedContentType, "multipart/form-data",
+                "Content-Type should be multipart/form-data.");
+            StringAssert.Contains(_capturingHandler.CapturedContentType, "boundary=",
+                "Content-Type must include a boundary parameter so the server can parse the body.");
+        }
+
+        [TestMethod]
+        public async Task UploadFile_TextFieldOnly_NoFile_BodyContainsTextValue()
+        {
+            var petApi = _host.Services.GetRequiredService<IPetApi>();
+
+            await petApi.UploadFileAsync(
+                petId: 1,
+                additionalMetadata: new Option<string>("testmetadata"));
+
+            Assert.IsNotNull(_capturingHandler.CapturedBody, "Body should not be null.");
+            StringAssert.Contains(_capturingHandler.CapturedBody, "testmetadata",
+                "Body should contain the additionalMetadata value.");
+        }
+
+        /// <summary>
+        /// Covers the case where an optional file and an optional text field are both supplied.
+        /// Ensures that adding text alongside a file does not strip the boundary.
+        /// </summary>
+        [TestMethod]
+        public async Task UploadFile_WithBothFileAndText_ContentTypeHasBoundary()
+        {
+            var petApi = _host.Services.GetRequiredService<IPetApi>();
+            using var stream = new MemoryStream(new byte[] { 1, 2, 3 });
+
+            await petApi.UploadFileAsync(
+                petId: 1,
+                file: new Option<FileParameter>(new FileParameter(stream)),
+                additionalMetadata: new Option<string>("testmetadata"));
+
+            Assert.IsNotNull(_capturingHandler.CapturedContentType,
+                "Content-Type header should not be null.");
+            StringAssert.Contains(_capturingHandler.CapturedContentType, "multipart/form-data",
+                "Content-Type should be multipart/form-data.");
+            StringAssert.Contains(_capturingHandler.CapturedContentType, "boundary=",
+                "Content-Type must include a boundary parameter.");
+        }
+
+        [TestMethod]
+        public async Task UploadFile_WithBothFileAndText_BodyContainsBothFields()
+        {
+            var petApi = _host.Services.GetRequiredService<IPetApi>();
+            using var stream = new MemoryStream(new byte[] { 1, 2, 3 });
+
+            await petApi.UploadFileAsync(
+                petId: 1,
+                file: new Option<FileParameter>(new FileParameter(stream)),
+                additionalMetadata: new Option<string>("testmetadata"));
+
+            Assert.IsNotNull(_capturingHandler.CapturedBody, "Body should not be null.");
+            StringAssert.Contains(_capturingHandler.CapturedBody, "name=file",
+                "Body should contain a part named 'file'.");
+            StringAssert.Contains(_capturingHandler.CapturedBody, "testmetadata",
+                "Body should contain the additionalMetadata value.");
+        }
+
+        /// <summary>
+        /// Covers UploadFileWithRequiredFile: a required (non-optional) binary file param.
+        /// Tests the required-file code path in the template, which differs from optional files.
+        /// </summary>
+        [TestMethod]
+        public async Task UploadFileWithRequiredFile_RequiredFileOnly_ContentTypeHasBoundary()
+        {
+            var petApi = _host.Services.GetRequiredService<IPetApi>();
+            using var stream = new MemoryStream(new byte[] { 7, 8, 9 });
+
+            await petApi.UploadFileWithRequiredFileAsync(petId: 1, requiredFile: new FileParameter(stream));
+
+            Assert.IsNotNull(_capturingHandler.CapturedContentType,
+                "Content-Type header should not be null.");
+            StringAssert.Contains(_capturingHandler.CapturedContentType, "multipart/form-data",
+                "Content-Type should be multipart/form-data.");
+            StringAssert.Contains(_capturingHandler.CapturedContentType, "boundary=",
+                "Content-Type must include a boundary parameter.");
+        }
+
+        [TestMethod]
+        public async Task UploadFileWithRequiredFile_RequiredFileOnly_BodyContainsCorrectFieldName()
+        {
+            var petApi = _host.Services.GetRequiredService<IPetApi>();
+            using var stream = new MemoryStream(new byte[] { 7, 8, 9 });
+
+            await petApi.UploadFileWithRequiredFileAsync(petId: 1, requiredFile: new FileParameter(stream));
+
+            Assert.IsNotNull(_capturingHandler.CapturedBody, "Body should not be null.");
+            StringAssert.Contains(_capturingHandler.CapturedBody, "name=requiredFile",
+                "Multipart part should use the field name 'requiredFile' as defined in the spec.");
+        }
+
+        [TestMethod]
+        public async Task UploadFileWithRequiredFile_WithTextAndFile_ContentTypeHasBoundary()
+        {
+            var petApi = _host.Services.GetRequiredService<IPetApi>();
+            using var stream = new MemoryStream(new byte[] { 7, 8, 9 });
+
+            await petApi.UploadFileWithRequiredFileAsync(
+                petId: 1,
+                requiredFile: new FileParameter(stream),
+                additionalMetadata: new Option<string>("testmetadata"));
+
+            Assert.IsNotNull(_capturingHandler.CapturedContentType,
+                "Content-Type header should not be null.");
+            StringAssert.Contains(_capturingHandler.CapturedContentType, "multipart/form-data",
+                "Content-Type should be multipart/form-data.");
+            StringAssert.Contains(_capturingHandler.CapturedContentType, "boundary=",
+                "Adding text fields alongside binary fields must not strip the boundary.");
+        }
+
+        [TestMethod]
+        public async Task UploadFileWithRequiredFile_WithTextAndFile_BodyContainsBothFields()
+        {
+            var petApi = _host.Services.GetRequiredService<IPetApi>();
+            using var stream = new MemoryStream(new byte[] { 7, 8, 9 });
+
+            await petApi.UploadFileWithRequiredFileAsync(
+                petId: 1,
+                requiredFile: new FileParameter(stream),
+                additionalMetadata: new Option<string>("testmetadata"));
+
+            Assert.IsNotNull(_capturingHandler.CapturedBody, "Body should not be null.");
+            StringAssert.Contains(_capturingHandler.CapturedBody, "name=requiredFile",
+                "Body should contain a part named 'requiredFile'.");
+            StringAssert.Contains(_capturingHandler.CapturedBody, "testmetadata",
+                "Body should contain the additionalMetadata value.");
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/.openapi-generator/FILES
index ab28c754b4b1..a3e02b328e0a 100644
--- a/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/.openapi-generator/FILES
@@ -140,6 +140,7 @@ src/Org.OpenAPITools/Client/DateOnlyNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningToken.cs
diff --git a/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/api/openapi.yaml b/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/api/openapi.yaml
index d8106a5755fc..ca451f3fb832 100644
--- a/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/api/openapi.yaml
+++ b/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/api/openapi.yaml
@@ -331,6 +331,40 @@ paths:
       summary: uploads an image
       tags:
       - pet
+  /pet/{petId}/uploadImages:
+    post:
+      description: ""
+      operationId: uploadFiles
+      parameters:
+      - description: ID of pet to update
+        explode: false
+        in: path
+        name: petId
+        required: true
+        schema:
+          format: int64
+          type: integer
+        style: simple
+      requestBody:
+        content:
+          multipart/form-data:
+            schema:
+              $ref: "#/components/schemas/uploadFiles_request"
+        required: true
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ApiResponse"
+          description: successful operation
+      security:
+      - petstore_auth:
+        - write:pets
+        - read:pets
+      summary: uploads an images
+      tags:
+      - pet
   /store/inventory:
     get:
       description: Returns a map of status codes to quantities
@@ -2924,6 +2958,16 @@ components:
           format: binary
           type: string
       type: object
+    uploadFiles_request:
+      properties:
+        files:
+          items:
+            format: binary
+            type: string
+          type: array
+      required:
+      - files
+      type: object
     testEnumParameters_request:
       properties:
         enum_form_string_array:
diff --git a/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/docs/apis/PetApi.md b/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/docs/apis/PetApi.md
index 2826ea00f728..b42ee516b313 100644
--- a/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/docs/apis/PetApi.md
+++ b/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/docs/apis/PetApi.md
@@ -13,6 +13,7 @@ All URIs are relative to *http://petstore.swagger.io:80/v2*
 | [**UpdatePetWithForm**](PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data |
 | [**UploadFile**](PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image |
 | [**UploadFileWithRequiredFile**](PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required) |
+| [**UploadFiles**](PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images |
 
 <a id="addpet"></a>
 # **AddPet**
@@ -341,3 +342,38 @@ uploads an image (required)
 
 [[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
 
+<a id="uploadfiles"></a>
+# **UploadFiles**
+> ApiResponse UploadFiles (List<System.IO.Stream> files, long petId)
+
+uploads an images
+
+
+### Parameters
+
+| Name | Type | Description | Notes |
+|------|------|-------------|-------|
+| **files** | **List&lt;System.IO.Stream&gt;** |  |  |
+| **petId** | **long** | ID of pet to update |  |
+
+### Return type
+
+[**ApiResponse**](ApiResponse.md)
+
+### Authorization
+
+[petstore_auth](../README.md#petstore_auth)
+
+### HTTP request headers
+
+ - **Content-Type**: multipart/form-data
+ - **Accept**: application/json
+
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **200** | successful operation |  -  |
+
+[[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
+
diff --git a/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs b/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
index 406dbc964a6d..d207bb93dc69 100644
--- a/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
@@ -196,7 +196,7 @@ public async Task TestEndpointParametersAsyncTest()
             string patternWithoutDelimiter = default!;
             byte[] varByte = default!;
             double varDouble = default!;
-            Client.Option<System.IO.Stream> binary = default!;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> binary = default!;
             Client.Option<string> callback = default!;
             Client.Option<DateOnly> date = default!;
             Client.Option<DateTime> dateTime = default!;
diff --git a/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/src/Org.OpenAPITools.Test/Api/PetApiTests.cs b/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
index 49e7b21b53c2..6bb1f953987c 100644
--- a/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
@@ -137,7 +137,7 @@ public async Task UploadFileAsyncTest()
         {
             long petId = default!;
             Client.Option<string> additionalMetadata = default!;
-            Client.Option<System.IO.Stream> file = default!;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> file = default!;
             var response = await _instance.UploadFileAsync(petId, additionalMetadata, file);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
@@ -150,11 +150,24 @@ public async Task UploadFileAsyncTest()
         public async Task UploadFileWithRequiredFileAsyncTest()
         {
             long petId = default!;
-            System.IO.Stream requiredFile = default!;
+            Org.OpenAPITools.Client.FileParameter requiredFile = default!;
             Client.Option<string> additionalMetadata = default!;
             var response = await _instance.UploadFileWithRequiredFileAsync(petId, requiredFile, additionalMetadata);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
         }
+
+        /// <summary>
+        /// Test UploadFiles
+        /// </summary>
+        [Fact (Skip = "not implemented")]
+        public async Task UploadFilesAsyncTest()
+        {
+            List<Org.OpenAPITools.Client.FileParameter> files = default!;
+            long petId = default!;
+            var response = await _instance.UploadFilesAsync(files, petId);
+            var model = response.Ok();
+            Assert.IsType<ApiResponse>(model);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/src/Org.OpenAPITools/Api/DefaultApi.cs b/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/src/Org.OpenAPITools/Api/DefaultApi.cs
index 2391c7e1ee03..46b798fe32ca 100644
--- a/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/src/Org.OpenAPITools/Api/DefaultApi.cs
+++ b/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/src/Org.OpenAPITools/Api/DefaultApi.cs
@@ -766,15 +766,12 @@ public async Task<IGetCountryApiResponse> GetCountryAsync(string country, System
                         ? "/country"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/country");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("country", ClientUtils.ParameterToString(country)));
 
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
-
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("country", ClientUtils.ParameterToString(country)));
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
 
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -782,11 +779,6 @@ public async Task<IGetCountryApiResponse> GetCountryAsync(string country, System
                         "application/x-www-form-urlencoded"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/src/Org.OpenAPITools/Api/FakeApi.cs b/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/src/Org.OpenAPITools/Api/FakeApi.cs
index 262a94ef2520..54a1c8c85360 100644
--- a/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/src/Org.OpenAPITools/Api/FakeApi.cs
+++ b/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/src/Org.OpenAPITools/Api/FakeApi.cs
@@ -332,7 +332,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -356,7 +356,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>?&gt;</returns>
-        Task<ITestEndpointParametersApiResponse?> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse?> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// To test enum parameters
@@ -4082,7 +4082,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<System.IO.Stream> binary, ref Option<string> callback, ref Option<DateOnly> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
+        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<Org.OpenAPITools.Client.FileParameter> binary, ref Option<string> callback, ref Option<DateOnly> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
 
         /// <summary>
         /// Validates the request parameters
@@ -4094,7 +4094,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="password"></param>
         /// <param name="varString"></param>
         /// <returns></returns>
-        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<System.IO.Stream> binary, Option<string> callback, Option<string> password, Option<string> varString)
+        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<string> password, Option<string> varString)
         {
             if (patternWithoutDelimiter == null)
                 throw new ArgumentNullException(nameof(patternWithoutDelimiter));
@@ -4133,7 +4133,7 @@ private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLog = false;
             AfterTestEndpointParameters(ref suppressDefaultLog, apiResponseLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4160,7 +4160,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -4182,7 +4182,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorTestEndpointParameters(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4211,7 +4211,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트  Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -4232,7 +4232,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse?> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse?> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -4264,7 +4264,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -4283,51 +4283,48 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         ? "/fake"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("number", ClientUtils.ParameterToString(number)));
 
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("pattern_without_delimiter", ClientUtils.ParameterToString(patternWithoutDelimiter)));
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("byte", ClientUtils.ParameterToString(varByte)));
 
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("number", ClientUtils.ParameterToString(number)));
-
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("pattern_without_delimiter", ClientUtils.ParameterToString(patternWithoutDelimiter)));
-
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("byte", ClientUtils.ParameterToString(varByte)));
-
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("double", ClientUtils.ParameterToString(varDouble)));
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("double", ClientUtils.ParameterToString(varDouble)));
 
                     if (binary.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(binary.Value));
+                        throw new NotSupportedException("File parameters cannot be sent with application/x-www-form-urlencoded. Change the operation's content type to multipart/form-data.");
 
                     if (callback.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("callback", ClientUtils.ParameterToString(callback.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("callback", ClientUtils.ParameterToString(callback.Value)));
 
                     if (date.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("date", ClientUtils.ParameterToString(date.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("date", ClientUtils.ParameterToString(date.Value)));
 
                     if (dateTime.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("dateTime", ClientUtils.ParameterToString(dateTime.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("dateTime", ClientUtils.ParameterToString(dateTime.Value)));
 
                     if (int32.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("int32", ClientUtils.ParameterToString(int32.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("int32", ClientUtils.ParameterToString(int32.Value)));
 
                     if (int64.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("int64", ClientUtils.ParameterToString(int64.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("int64", ClientUtils.ParameterToString(int64.Value)));
 
                     if (integer.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("integer", ClientUtils.ParameterToString(integer.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("integer", ClientUtils.ParameterToString(integer.Value)));
 
                     if (password.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("password", ClientUtils.ParameterToString(password.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("password", ClientUtils.ParameterToString(password.Value)));
 
                     if (varFloat.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("float", ClientUtils.ParameterToString(varFloat.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("float", ClientUtils.ParameterToString(varFloat.Value)));
 
                     if (varString.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("string", ClientUtils.ParameterToString(varString.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("string", ClientUtils.ParameterToString(varString.Value)));
+
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -4342,11 +4339,6 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         "application/x-www-form-urlencoded"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -4639,17 +4631,16 @@ public async Task<ITestEnumParametersApiResponse> TestEnumParametersAsync(Option
                     if (enumHeaderStringArray.IsSet)
                         httpRequestMessageLocalVar.Headers.Add("enum_header_string_array", ClientUtils.ParameterToString(enumHeaderStringArray.Value));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
-
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (enumFormString.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("enum_form_string", ClientUtils.ParameterToString(enumFormString.Value)));
+                    if (enumFormString.IsSet)
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("enum_form_string", ClientUtils.ParameterToString(enumFormString.Value)));
 
                     if (enumFormStringArray.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("enum_form_string_array", ClientUtils.ParameterToString(enumFormStringArray.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("enum_form_string_array", ClientUtils.ParameterToString(enumFormStringArray.Value)));
+
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
 
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -4657,11 +4648,6 @@ public async Task<ITestEnumParametersApiResponse> TestEnumParametersAsync(Option
                         "application/x-www-form-urlencoded"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Get;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -5548,17 +5534,14 @@ public async Task<ITestJsonFormDataApiResponse> TestJsonFormDataAsync(string par
                         ? "/fake/jsonFormData"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/jsonFormData");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("param", ClientUtils.ParameterToString(param)));
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("param2", ClientUtils.ParameterToString(param2)));
 
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("param", ClientUtils.ParameterToString(param)));
-
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("param2", ClientUtils.ParameterToString(param2)));
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
 
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -5566,11 +5549,6 @@ public async Task<ITestJsonFormDataApiResponse> TestJsonFormDataAsync(string par
                         "application/x-www-form-urlencoded"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Get;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/src/Org.OpenAPITools/Api/PetApi.cs b/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/src/Org.OpenAPITools/Api/PetApi.cs
index 2d7e4dab0b84..c5de9cd55ad1 100644
--- a/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/src/Org.OpenAPITools/Api/PetApi.cs
+++ b/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/src/Org.OpenAPITools/Api/PetApi.cs
@@ -218,7 +218,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image
@@ -231,7 +231,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>?&gt;</returns>
-        Task<IUploadFileApiResponse?> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse?> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -245,7 +245,7 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -258,7 +258,32 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>?&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse?> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse?> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>?&gt;</returns>
+        Task<IUploadFilesApiResponse?> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
     }
 
     /// <summary>
@@ -417,6 +442,18 @@ public interface IUploadFileWithRequiredFileApiResponse : Org.OpenAPITools.Clien
         bool IsOk { get; }
     }
 
+    /// <summary>
+    /// The <see cref="IUploadFilesApiResponse"/>
+    /// </summary>
+    public interface IUploadFilesApiResponse : Org.OpenAPITools.Client.IApiResponse, IOk<Org.OpenAPITools.Model.ApiResponse?>
+    {
+        /// <summary>
+        /// Returns true if the response is 200 Ok
+        /// </summary>
+        /// <returns></returns>
+        bool IsOk { get; }
+    }
+
     /// <summary>
     /// Represents a collection of functions to interact with the API endpoints
     /// </summary>
@@ -601,6 +638,26 @@ internal void ExecuteOnErrorUploadFileWithRequiredFile(Exception exception)
         {
             OnErrorUploadFileWithRequiredFile?.Invoke(this, new ExceptionEventArgs(exception));
         }
+
+        /// <summary>
+        /// The event raised after the server response
+        /// </summary>
+        public event EventHandler<ApiResponseEventArgs>? OnUploadFiles;
+
+        /// <summary>
+        /// The event raised after an error querying the server
+        /// </summary>
+        public event EventHandler<ExceptionEventArgs>? OnErrorUploadFiles;
+
+        internal void ExecuteOnUploadFiles(PetApi.UploadFilesApiResponse apiResponse)
+        {
+            OnUploadFiles?.Invoke(this, new ApiResponseEventArgs(apiResponse));
+        }
+
+        internal void ExecuteOnErrorUploadFiles(Exception exception)
+        {
+            OnErrorUploadFiles?.Invoke(this, new ExceptionEventArgs(exception));
+        }
     }
 
     /// <summary>
@@ -2332,17 +2389,16 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (name.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("name", ClientUtils.ParameterToString(name.Value)));
+                    if (name.IsSet)
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("name", ClientUtils.ParameterToString(name.Value)));
 
                     if (status.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("status", ClientUtils.ParameterToString(status.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("status", ClientUtils.ParameterToString(status.Value)));
+
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -2357,11 +2413,6 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         "application/x-www-form-urlencoded"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -2461,7 +2512,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<System.IO.Stream> file);
+        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Validates the request parameters
@@ -2469,7 +2520,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
         /// <returns></returns>
-        private void ValidateUploadFile(Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void ValidateUploadFile(Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             if (additionalMetadata.IsSet && additionalMetadata.Value == null)
                 throw new ArgumentNullException(nameof(additionalMetadata));
@@ -2485,7 +2536,7 @@ private void ValidateUploadFile(Option<string> additionalMetadata, Option<System
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLog = false;
             AfterUploadFile(ref suppressDefaultLog, apiResponseLocalVar, petId, additionalMetadata, file);
@@ -2501,7 +2552,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2512,7 +2563,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, additionalMetadata, file);
@@ -2530,7 +2581,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// uploads an image 
@@ -2540,7 +2591,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse?> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse?> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2561,7 +2612,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2581,17 +2632,23 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImage");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (additionalMetadata.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
+                    if (additionalMetadata.IsSet)
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
 
                     if (file.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(file.Value));
+                    {
+                        var streamContentLocalVar = new StreamContent(file.Value.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "file", file.Value.FileName ?? "file");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -2606,11 +2663,6 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         "multipart/form-data"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json"
                     };
@@ -2751,7 +2803,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFileWithRequiredFile(ref long petId, ref System.IO.Stream requiredFile, ref Option<string> additionalMetadata);
+        partial void FormatUploadFileWithRequiredFile(ref long petId, ref Org.OpenAPITools.Client.FileParameter requiredFile, ref Option<string> additionalMetadata);
 
         /// <summary>
         /// Validates the request parameters
@@ -2759,7 +2811,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
         /// <returns></returns>
-        private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void ValidateUploadFileWithRequiredFile(Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             if (requiredFile == null)
                 throw new ArgumentNullException(nameof(requiredFile));
@@ -2775,7 +2827,7 @@ private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, O
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLog = false;
             AfterUploadFileWithRequiredFile(ref suppressDefaultLog, apiResponseLocalVar, petId, requiredFile, additionalMetadata);
@@ -2791,7 +2843,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2802,7 +2854,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFileWithRequiredFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, requiredFile, additionalMetadata);
@@ -2820,7 +2872,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// uploads an image (required) 
@@ -2830,7 +2882,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse?> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse?> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2851,7 +2903,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2871,16 +2923,22 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/{petId}/uploadImageWithRequiredFile");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    multipartContentLocalVar.Add(new StreamContent(requiredFile));
+                    {
+                        var streamContentLocalVar = new StreamContent(requiredFile.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "requiredFile", requiredFile.FileName ?? "requiredFile");
+                    }
 
                     if (additionalMetadata.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -2895,11 +2953,6 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         "multipart/form-data"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json",
                         "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
@@ -3040,5 +3093,283 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
 
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
+
+        partial void FormatUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files, ref long petId);
+
+        /// <summary>
+        /// Validates the request parameters
+        /// </summary>
+        /// <param name="files"></param>
+        /// <returns></returns>
+        private void ValidateUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files)
+        {
+            if (files == null)
+                throw new ArgumentNullException(nameof(files));
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void AfterUploadFilesDefaultImplementation(IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLog = false;
+            AfterUploadFiles(ref suppressDefaultLog, apiResponseLocalVar, files, petId);
+            if (!suppressDefaultLog)
+                Logger.LogInformation("{0,-9} | {1} | {2}", (apiResponseLocalVar.DownloadedAt - apiResponseLocalVar.RequestedAt).TotalSeconds, apiResponseLocalVar.StatusCode, apiResponseLocalVar.Path);
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="suppressDefaultLog"></param>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void AfterUploadFiles(ref bool suppressDefaultLog, IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// Logs exceptions that occur while retrieving the server response
+        /// </summary>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void OnErrorUploadFilesDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLogLocalVar = false;
+            OnErrorUploadFiles(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, files, petId);
+            if (!suppressDefaultLogLocalVar)
+                Logger.LogError(exceptionLocalVar, "An error occurred while sending the request to the server.");
+        }
+
+        /// <summary>
+        /// A partial method that gives developers a way to provide customized exception handling
+        /// </summary>
+        /// <param name="suppressDefaultLogLocalVar"></param>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void OnErrorUploadFiles(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse?> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            try
+            {
+                return await UploadFilesAsync(files, petId, cancellationToken).ConfigureAwait(false);
+            }
+            catch (Exception)
+            {
+                return null;
+            }
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            UriBuilder uriBuilderLocalVar = new UriBuilder();
+
+            try
+            {
+                ValidateUploadFiles(files);
+
+                FormatUploadFiles(files, ref petId);
+
+                using (HttpRequestMessage httpRequestMessageLocalVar = new HttpRequestMessage())
+                {
+                    uriBuilderLocalVar.Host = HttpClient.BaseAddress!.Host;
+                    uriBuilderLocalVar.Port = HttpClient.BaseAddress.Port;
+                    uriBuilderLocalVar.Scheme = HttpClient.BaseAddress.Scheme;
+                    uriBuilderLocalVar.Path = HttpClient.BaseAddress.AbsolutePath == "/"
+                        ? "/pet/{petId}/uploadImages"
+                        : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImages");
+                    uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
+
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
+
+                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
+
+                    foreach (Org.OpenAPITools.Client.FileParameter fileParameterLocalVar in files)
+                    {
+                        var streamContentLocalVar = new StreamContent(fileParameterLocalVar.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "files", fileParameterLocalVar.FileName ?? "files");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
+
+                    List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
+                    httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
+
+                    OAuthToken oauthTokenLocalVar1 = (OAuthToken) await OauthTokenProvider.GetAsync(cancellation: cancellationToken).ConfigureAwait(false);
+
+                    tokenBaseLocalVars.Add(oauthTokenLocalVar1);
+
+                    oauthTokenLocalVar1.UseInHeader(httpRequestMessageLocalVar, "");
+
+                    string[] contentTypes = new string[] {
+                        "multipart/form-data"
+                    };
+
+                    string[] acceptLocalVars = new string[] {
+                        "application/json"
+                    };
+
+                    IEnumerable<MediaTypeWithQualityHeaderValue> acceptHeaderValuesLocalVar = ClientUtils.SelectHeaderAcceptArray(acceptLocalVars);
+
+                    foreach (var acceptLocalVar in acceptHeaderValuesLocalVar)
+                        httpRequestMessageLocalVar.Headers.Accept.Add(acceptLocalVar);
+
+                    httpRequestMessageLocalVar.Method = HttpMethod.Post;
+
+                    DateTime requestedAtLocalVar = DateTime.UtcNow;
+
+                    using (HttpResponseMessage httpResponseMessageLocalVar = await HttpClient.SendAsync(httpRequestMessageLocalVar, cancellationToken).ConfigureAwait(false))
+                    {
+                        ILogger<UploadFilesApiResponse> apiResponseLoggerLocalVar = LoggerFactory.CreateLogger<UploadFilesApiResponse>();
+                        UploadFilesApiResponse apiResponseLocalVar;
+
+                        switch ((int)httpResponseMessageLocalVar.StatusCode) {
+                            default: {
+                                string responseContentLocalVar = await httpResponseMessageLocalVar.Content.ReadAsStringAsync(cancellationToken).ConfigureAwait(false);
+                                apiResponseLocalVar = new(apiResponseLoggerLocalVar, httpRequestMessageLocalVar, httpResponseMessageLocalVar, responseContentLocalVar, "/pet/{petId}/uploadImages", requestedAtLocalVar, _jsonSerializerOptions);
+
+                                break;
+                            }
+                        }
+
+                        AfterUploadFilesDefaultImplementation(apiResponseLocalVar, files, petId);
+
+                        Events.ExecuteOnUploadFiles(apiResponseLocalVar);
+
+                        if (apiResponseLocalVar.StatusCode == (HttpStatusCode) 429)
+                            foreach(TokenBase tokenBaseLocalVar in tokenBaseLocalVars)
+                                tokenBaseLocalVar.BeginRateLimit();
+
+                        return apiResponseLocalVar;
+                    }
+                }
+            }
+            catch(Exception e)
+            {
+                OnErrorUploadFilesDefaultImplementation(e, "/pet/{petId}/uploadImages", uriBuilderLocalVar.Path, files, petId);
+                Events.ExecuteOnErrorUploadFiles(e);
+                throw;
+            }
+        }
+
+        /// <summary>
+        /// The <see cref="UploadFilesApiResponse"/>
+        /// </summary>
+        public partial class UploadFilesApiResponse : Org.OpenAPITools.Client.ApiResponse, IUploadFilesApiResponse
+        {
+            /// <summary>
+            /// The logger
+            /// </summary>
+            public ILogger<UploadFilesApiResponse> Logger { get; }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="rawContent"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, string rawContent, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, rawContent, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="contentStream"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, System.IO.Stream contentStream, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, contentStream, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            partial void OnCreated(global::System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage);
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public bool IsOk => 200 == (int)StatusCode;
+
+            /// <summary>
+            /// Deserializes the response if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public Org.OpenAPITools.Model.ApiResponse? Ok()
+            {
+                // This logic may be modified with the AsModel.mustache template
+                return IsOk
+                    ? System.Text.Json.JsonSerializer.Deserialize<Org.OpenAPITools.Model.ApiResponse>(RawContent, _jsonSerializerOptions)
+                    : null;
+            }
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok and the deserialized response is not null
+            /// </summary>
+            /// <param name="result"></param>
+            /// <returns></returns>
+            public bool TryOk([NotNullWhen(true)]out Org.OpenAPITools.Model.ApiResponse? result)
+            {
+                result = null;
+
+                try
+                {
+                    result = Ok();
+                } catch (Exception e)
+                {
+                    OnDeserializationErrorDefaultImplementation(e, (HttpStatusCode)200);
+                }
+
+                return result != null;
+            }
+
+            private void OnDeserializationErrorDefaultImplementation(Exception exception, HttpStatusCode httpStatusCode)
+            {
+                bool suppressDefaultLog = false;
+                OnDeserializationError(ref suppressDefaultLog, exception, httpStatusCode);
+                if (!suppressDefaultLog)
+                    Logger.LogError(exception, "An error occurred while deserializing the {code} response.", httpStatusCode);
+            }
+
+            partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..77779fe7d75a
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net8/NullReferenceTypes/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,42 @@
+// <auto-generated>
+/*
+ * OpenAPI Petstore
+ *
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+#nullable enable
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string? FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string? fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net8/OneOf/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net8/OneOf/.openapi-generator/FILES
index a36efde4422e..cfb76c7ed0ac 100644
--- a/samples/client/petstore/csharp/generichost/net8/OneOf/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net8/OneOf/.openapi-generator/FILES
@@ -26,6 +26,7 @@ src/Org.OpenAPITools/Client/DateOnlyNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/JsonSerializerOptionsProvider.cs
 src/Org.OpenAPITools/Client/Option.cs
diff --git a/samples/client/petstore/csharp/generichost/net8/OneOf/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net8/OneOf/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..e629f4afdaec
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net8/OneOf/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,42 @@
+// <auto-generated>
+/*
+ * fruity
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * The version of the OpenAPI document: 0.0.1
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+#nullable enable
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string? FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string? fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net8/Petstore/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net8/Petstore/.openapi-generator/FILES
index ab28c754b4b1..a3e02b328e0a 100644
--- a/samples/client/petstore/csharp/generichost/net8/Petstore/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net8/Petstore/.openapi-generator/FILES
@@ -140,6 +140,7 @@ src/Org.OpenAPITools/Client/DateOnlyNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningToken.cs
diff --git a/samples/client/petstore/csharp/generichost/net8/Petstore/api/openapi.yaml b/samples/client/petstore/csharp/generichost/net8/Petstore/api/openapi.yaml
index d8106a5755fc..ca451f3fb832 100644
--- a/samples/client/petstore/csharp/generichost/net8/Petstore/api/openapi.yaml
+++ b/samples/client/petstore/csharp/generichost/net8/Petstore/api/openapi.yaml
@@ -331,6 +331,40 @@ paths:
       summary: uploads an image
       tags:
       - pet
+  /pet/{petId}/uploadImages:
+    post:
+      description: ""
+      operationId: uploadFiles
+      parameters:
+      - description: ID of pet to update
+        explode: false
+        in: path
+        name: petId
+        required: true
+        schema:
+          format: int64
+          type: integer
+        style: simple
+      requestBody:
+        content:
+          multipart/form-data:
+            schema:
+              $ref: "#/components/schemas/uploadFiles_request"
+        required: true
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ApiResponse"
+          description: successful operation
+      security:
+      - petstore_auth:
+        - write:pets
+        - read:pets
+      summary: uploads an images
+      tags:
+      - pet
   /store/inventory:
     get:
       description: Returns a map of status codes to quantities
@@ -2924,6 +2958,16 @@ components:
           format: binary
           type: string
       type: object
+    uploadFiles_request:
+      properties:
+        files:
+          items:
+            format: binary
+            type: string
+          type: array
+      required:
+      - files
+      type: object
     testEnumParameters_request:
       properties:
         enum_form_string_array:
diff --git a/samples/client/petstore/csharp/generichost/net8/Petstore/docs/apis/PetApi.md b/samples/client/petstore/csharp/generichost/net8/Petstore/docs/apis/PetApi.md
index 2826ea00f728..b42ee516b313 100644
--- a/samples/client/petstore/csharp/generichost/net8/Petstore/docs/apis/PetApi.md
+++ b/samples/client/petstore/csharp/generichost/net8/Petstore/docs/apis/PetApi.md
@@ -13,6 +13,7 @@ All URIs are relative to *http://petstore.swagger.io:80/v2*
 | [**UpdatePetWithForm**](PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data |
 | [**UploadFile**](PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image |
 | [**UploadFileWithRequiredFile**](PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required) |
+| [**UploadFiles**](PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images |
 
 <a id="addpet"></a>
 # **AddPet**
@@ -341,3 +342,38 @@ uploads an image (required)
 
 [[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
 
+<a id="uploadfiles"></a>
+# **UploadFiles**
+> ApiResponse UploadFiles (List<System.IO.Stream> files, long petId)
+
+uploads an images
+
+
+### Parameters
+
+| Name | Type | Description | Notes |
+|------|------|-------------|-------|
+| **files** | **List&lt;System.IO.Stream&gt;** |  |  |
+| **petId** | **long** | ID of pet to update |  |
+
+### Return type
+
+[**ApiResponse**](ApiResponse.md)
+
+### Authorization
+
+[petstore_auth](../README.md#petstore_auth)
+
+### HTTP request headers
+
+ - **Content-Type**: multipart/form-data
+ - **Accept**: application/json
+
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **200** | successful operation |  -  |
+
+[[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
+
diff --git a/samples/client/petstore/csharp/generichost/net8/Petstore/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs b/samples/client/petstore/csharp/generichost/net8/Petstore/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
index 66769b3aee6a..fed093fb206f 100644
--- a/samples/client/petstore/csharp/generichost/net8/Petstore/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/net8/Petstore/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
@@ -196,7 +196,7 @@ public async Task TestEndpointParametersAsyncTest()
             string patternWithoutDelimiter = default;
             byte[] varByte = default;
             double varDouble = default;
-            Client.Option<System.IO.Stream> binary = default;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> binary = default;
             Client.Option<string> callback = default;
             Client.Option<DateOnly> date = default;
             Client.Option<DateTime> dateTime = default;
diff --git a/samples/client/petstore/csharp/generichost/net8/Petstore/src/Org.OpenAPITools.Test/Api/PetApiTests.cs b/samples/client/petstore/csharp/generichost/net8/Petstore/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
index 215e88093797..e9b05337bb59 100644
--- a/samples/client/petstore/csharp/generichost/net8/Petstore/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/net8/Petstore/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
@@ -137,7 +137,7 @@ public async Task UploadFileAsyncTest()
         {
             long petId = default;
             Client.Option<string> additionalMetadata = default;
-            Client.Option<System.IO.Stream> file = default;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> file = default;
             var response = await _instance.UploadFileAsync(petId, additionalMetadata, file);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
@@ -150,11 +150,24 @@ public async Task UploadFileAsyncTest()
         public async Task UploadFileWithRequiredFileAsyncTest()
         {
             long petId = default;
-            System.IO.Stream requiredFile = default;
+            Org.OpenAPITools.Client.FileParameter requiredFile = default;
             Client.Option<string> additionalMetadata = default;
             var response = await _instance.UploadFileWithRequiredFileAsync(petId, requiredFile, additionalMetadata);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
         }
+
+        /// <summary>
+        /// Test UploadFiles
+        /// </summary>
+        [Fact (Skip = "not implemented")]
+        public async Task UploadFilesAsyncTest()
+        {
+            List<Org.OpenAPITools.Client.FileParameter> files = default;
+            long petId = default;
+            var response = await _instance.UploadFilesAsync(files, petId);
+            var model = response.Ok();
+            Assert.IsType<ApiResponse>(model);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/net8/Petstore/src/Org.OpenAPITools/Api/DefaultApi.cs b/samples/client/petstore/csharp/generichost/net8/Petstore/src/Org.OpenAPITools/Api/DefaultApi.cs
index 3c26a27185e6..44d52e7e1090 100644
--- a/samples/client/petstore/csharp/generichost/net8/Petstore/src/Org.OpenAPITools/Api/DefaultApi.cs
+++ b/samples/client/petstore/csharp/generichost/net8/Petstore/src/Org.OpenAPITools/Api/DefaultApi.cs
@@ -764,27 +764,19 @@ public async Task<IGetCountryApiResponse> GetCountryAsync(string country, System
                         ? "/country"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/country");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("country", ClientUtils.ParameterToString(country)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/net8/Petstore/src/Org.OpenAPITools/Api/FakeApi.cs b/samples/client/petstore/csharp/generichost/net8/Petstore/src/Org.OpenAPITools/Api/FakeApi.cs
index 01aaf0ccbd85..482421f8c4ea 100644
--- a/samples/client/petstore/csharp/generichost/net8/Petstore/src/Org.OpenAPITools/Api/FakeApi.cs
+++ b/samples/client/petstore/csharp/generichost/net8/Petstore/src/Org.OpenAPITools/Api/FakeApi.cs
@@ -330,7 +330,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -354,7 +354,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// To test enum parameters
@@ -4080,7 +4080,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<System.IO.Stream> binary, ref Option<string> callback, ref Option<DateOnly> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
+        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<Org.OpenAPITools.Client.FileParameter> binary, ref Option<string> callback, ref Option<DateOnly> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
 
         /// <summary>
         /// Validates the request parameters
@@ -4092,7 +4092,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="password"></param>
         /// <param name="varString"></param>
         /// <returns></returns>
-        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<System.IO.Stream> binary, Option<string> callback, Option<string> password, Option<string> varString)
+        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<string> password, Option<string> varString)
         {
             if (patternWithoutDelimiter == null)
                 throw new ArgumentNullException(nameof(patternWithoutDelimiter));
@@ -4131,7 +4131,7 @@ private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLog = false;
             AfterTestEndpointParameters(ref suppressDefaultLog, apiResponseLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4158,7 +4158,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -4180,7 +4180,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorTestEndpointParameters(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4209,7 +4209,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트  Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -4230,7 +4230,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -4262,7 +4262,7 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDe
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -4281,14 +4281,8 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         ? "/fake"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("number", ClientUtils.ParameterToString(number)));
 
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("pattern_without_delimiter", ClientUtils.ParameterToString(patternWithoutDelimiter)));
@@ -4298,7 +4292,7 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("double", ClientUtils.ParameterToString(varDouble)));
 
                     if (binary.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(binary.Value));
+                        throw new NotSupportedException("File parameters cannot be sent with application/x-www-form-urlencoded. Change the operation's content type to multipart/form-data.");
 
                     if (callback.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("callback", ClientUtils.ParameterToString(callback.Value)));
@@ -4327,6 +4321,9 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                     if (varString.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("string", ClientUtils.ParameterToString(varString.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -4340,11 +4337,6 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -4637,29 +4629,23 @@ public async Task<ITestEnumParametersApiResponse> TestEnumParametersAsync(Option
                     if (enumHeaderStringArray.IsSet)
                         httpRequestMessageLocalVar.Headers.Add("enum_header_string_array", ClientUtils.ParameterToString(enumHeaderStringArray.Value));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (enumFormString.IsSet)
+                    if (enumFormString.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("enum_form_string", ClientUtils.ParameterToString(enumFormString.Value)));
 
                     if (enumFormStringArray.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("enum_form_string_array", ClientUtils.ParameterToString(enumFormStringArray.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Get;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -5546,29 +5532,21 @@ public async Task<ITestJsonFormDataApiResponse> TestJsonFormDataAsync(string par
                         ? "/fake/jsonFormData"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/jsonFormData");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("param", ClientUtils.ParameterToString(param)));
 
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("param2", ClientUtils.ParameterToString(param2)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Get;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/net8/Petstore/src/Org.OpenAPITools/Api/PetApi.cs b/samples/client/petstore/csharp/generichost/net8/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
index a1817e3df697..da4dfd225bc4 100644
--- a/samples/client/petstore/csharp/generichost/net8/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
+++ b/samples/client/petstore/csharp/generichost/net8/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
@@ -216,7 +216,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image
@@ -229,7 +229,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -243,7 +243,7 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -256,7 +256,32 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        Task<IUploadFilesApiResponse> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
     }
 
     /// <summary>
@@ -415,6 +440,18 @@ public interface IUploadFileWithRequiredFileApiResponse : Org.OpenAPITools.Clien
         bool IsOk { get; }
     }
 
+    /// <summary>
+    /// The <see cref="IUploadFilesApiResponse"/>
+    /// </summary>
+    public interface IUploadFilesApiResponse : Org.OpenAPITools.Client.IApiResponse, IOk<Org.OpenAPITools.Model.ApiResponse>
+    {
+        /// <summary>
+        /// Returns true if the response is 200 Ok
+        /// </summary>
+        /// <returns></returns>
+        bool IsOk { get; }
+    }
+
     /// <summary>
     /// Represents a collection of functions to interact with the API endpoints
     /// </summary>
@@ -599,6 +636,26 @@ internal void ExecuteOnErrorUploadFileWithRequiredFile(Exception exception)
         {
             OnErrorUploadFileWithRequiredFile?.Invoke(this, new ExceptionEventArgs(exception));
         }
+
+        /// <summary>
+        /// The event raised after the server response
+        /// </summary>
+        public event EventHandler<ApiResponseEventArgs> OnUploadFiles;
+
+        /// <summary>
+        /// The event raised after an error querying the server
+        /// </summary>
+        public event EventHandler<ExceptionEventArgs> OnErrorUploadFiles;
+
+        internal void ExecuteOnUploadFiles(PetApi.UploadFilesApiResponse apiResponse)
+        {
+            OnUploadFiles?.Invoke(this, new ApiResponseEventArgs(apiResponse));
+        }
+
+        internal void ExecuteOnErrorUploadFiles(Exception exception)
+        {
+            OnErrorUploadFiles?.Invoke(this, new ExceptionEventArgs(exception));
+        }
     }
 
     /// <summary>
@@ -2330,18 +2387,17 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (name.IsSet)
+                    if (name.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("name", ClientUtils.ParameterToString(name.Value)));
 
                     if (status.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("status", ClientUtils.ParameterToString(status.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -2355,11 +2411,6 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -2459,7 +2510,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<System.IO.Stream> file);
+        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Validates the request parameters
@@ -2467,7 +2518,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
         /// <returns></returns>
-        private void ValidateUploadFile(Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void ValidateUploadFile(Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             if (additionalMetadata.IsSet && additionalMetadata.Value == null)
                 throw new ArgumentNullException(nameof(additionalMetadata));
@@ -2483,7 +2534,7 @@ private void ValidateUploadFile(Option<string> additionalMetadata, Option<System
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLog = false;
             AfterUploadFile(ref suppressDefaultLog, apiResponseLocalVar, petId, additionalMetadata, file);
@@ -2499,7 +2550,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2510,7 +2561,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, additionalMetadata, file);
@@ -2528,7 +2579,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// uploads an image 
@@ -2538,7 +2589,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2559,7 +2610,7 @@ public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, O
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2579,17 +2630,23 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImage");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (additionalMetadata.IsSet)
+                    if (additionalMetadata.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
 
                     if (file.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(file.Value));
+                    {
+                        var streamContentLocalVar = new StreamContent(file.Value.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "file", file.Value.FileName ?? "file");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -2604,11 +2661,6 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         "multipart/form-data"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json"
                     };
@@ -2749,7 +2801,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFileWithRequiredFile(ref long petId, ref System.IO.Stream requiredFile, ref Option<string> additionalMetadata);
+        partial void FormatUploadFileWithRequiredFile(ref long petId, ref Org.OpenAPITools.Client.FileParameter requiredFile, ref Option<string> additionalMetadata);
 
         /// <summary>
         /// Validates the request parameters
@@ -2757,7 +2809,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
         /// <returns></returns>
-        private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void ValidateUploadFileWithRequiredFile(Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             if (requiredFile == null)
                 throw new ArgumentNullException(nameof(requiredFile));
@@ -2773,7 +2825,7 @@ private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, O
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLog = false;
             AfterUploadFileWithRequiredFile(ref suppressDefaultLog, apiResponseLocalVar, petId, requiredFile, additionalMetadata);
@@ -2789,7 +2841,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2800,7 +2852,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFileWithRequiredFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, requiredFile, additionalMetadata);
@@ -2818,7 +2870,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// uploads an image (required) 
@@ -2828,7 +2880,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2849,7 +2901,7 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2869,17 +2921,23 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/{petId}/uploadImageWithRequiredFile");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    multipartContentLocalVar.Add(new StreamContent(requiredFile));
+                    {
+                        var streamContentLocalVar = new StreamContent(requiredFile.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "requiredFile", requiredFile.FileName ?? "requiredFile");
+                    }
 
                     if (additionalMetadata.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
 
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -2893,11 +2951,6 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         "multipart/form-data"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json",
                         "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
@@ -3038,5 +3091,283 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
 
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
+
+        partial void FormatUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files, ref long petId);
+
+        /// <summary>
+        /// Validates the request parameters
+        /// </summary>
+        /// <param name="files"></param>
+        /// <returns></returns>
+        private void ValidateUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files)
+        {
+            if (files == null)
+                throw new ArgumentNullException(nameof(files));
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void AfterUploadFilesDefaultImplementation(IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLog = false;
+            AfterUploadFiles(ref suppressDefaultLog, apiResponseLocalVar, files, petId);
+            if (!suppressDefaultLog)
+                Logger.LogInformation("{0,-9} | {1} | {2}", (apiResponseLocalVar.DownloadedAt - apiResponseLocalVar.RequestedAt).TotalSeconds, apiResponseLocalVar.StatusCode, apiResponseLocalVar.Path);
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="suppressDefaultLog"></param>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void AfterUploadFiles(ref bool suppressDefaultLog, IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// Logs exceptions that occur while retrieving the server response
+        /// </summary>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void OnErrorUploadFilesDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLogLocalVar = false;
+            OnErrorUploadFiles(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, files, petId);
+            if (!suppressDefaultLogLocalVar)
+                Logger.LogError(exceptionLocalVar, "An error occurred while sending the request to the server.");
+        }
+
+        /// <summary>
+        /// A partial method that gives developers a way to provide customized exception handling
+        /// </summary>
+        /// <param name="suppressDefaultLogLocalVar"></param>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void OnErrorUploadFiles(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            try
+            {
+                return await UploadFilesAsync(files, petId, cancellationToken).ConfigureAwait(false);
+            }
+            catch (Exception)
+            {
+                return null;
+            }
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            UriBuilder uriBuilderLocalVar = new UriBuilder();
+
+            try
+            {
+                ValidateUploadFiles(files);
+
+                FormatUploadFiles(files, ref petId);
+
+                using (HttpRequestMessage httpRequestMessageLocalVar = new HttpRequestMessage())
+                {
+                    uriBuilderLocalVar.Host = HttpClient.BaseAddress.Host;
+                    uriBuilderLocalVar.Port = HttpClient.BaseAddress.Port;
+                    uriBuilderLocalVar.Scheme = HttpClient.BaseAddress.Scheme;
+                    uriBuilderLocalVar.Path = HttpClient.BaseAddress.AbsolutePath == "/"
+                        ? "/pet/{petId}/uploadImages"
+                        : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImages");
+                    uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
+
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
+
+                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+
+                    List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
+
+                    foreach (Org.OpenAPITools.Client.FileParameter fileParameterLocalVar in files)
+                    {
+                        var streamContentLocalVar = new StreamContent(fileParameterLocalVar.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "files", fileParameterLocalVar.FileName ?? "files");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
+
+                    List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
+                    httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
+
+                    OAuthToken oauthTokenLocalVar1 = (OAuthToken) await OauthTokenProvider.GetAsync(cancellation: cancellationToken).ConfigureAwait(false);
+
+                    tokenBaseLocalVars.Add(oauthTokenLocalVar1);
+
+                    oauthTokenLocalVar1.UseInHeader(httpRequestMessageLocalVar, "");
+
+                    string[] contentTypes = new string[] {
+                        "multipart/form-data"
+                    };
+
+                    string[] acceptLocalVars = new string[] {
+                        "application/json"
+                    };
+
+                    IEnumerable<MediaTypeWithQualityHeaderValue> acceptHeaderValuesLocalVar = ClientUtils.SelectHeaderAcceptArray(acceptLocalVars);
+
+                    foreach (var acceptLocalVar in acceptHeaderValuesLocalVar)
+                        httpRequestMessageLocalVar.Headers.Accept.Add(acceptLocalVar);
+
+                    httpRequestMessageLocalVar.Method = HttpMethod.Post;
+
+                    DateTime requestedAtLocalVar = DateTime.UtcNow;
+
+                    using (HttpResponseMessage httpResponseMessageLocalVar = await HttpClient.SendAsync(httpRequestMessageLocalVar, cancellationToken).ConfigureAwait(false))
+                    {
+                        ILogger<UploadFilesApiResponse> apiResponseLoggerLocalVar = LoggerFactory.CreateLogger<UploadFilesApiResponse>();
+                        UploadFilesApiResponse apiResponseLocalVar;
+
+                        switch ((int)httpResponseMessageLocalVar.StatusCode) {
+                            default: {
+                                string responseContentLocalVar = await httpResponseMessageLocalVar.Content.ReadAsStringAsync(cancellationToken).ConfigureAwait(false);
+                                apiResponseLocalVar = new(apiResponseLoggerLocalVar, httpRequestMessageLocalVar, httpResponseMessageLocalVar, responseContentLocalVar, "/pet/{petId}/uploadImages", requestedAtLocalVar, _jsonSerializerOptions);
+
+                                break;
+                            }
+                        }
+
+                        AfterUploadFilesDefaultImplementation(apiResponseLocalVar, files, petId);
+
+                        Events.ExecuteOnUploadFiles(apiResponseLocalVar);
+
+                        if (apiResponseLocalVar.StatusCode == (HttpStatusCode) 429)
+                            foreach(TokenBase tokenBaseLocalVar in tokenBaseLocalVars)
+                                tokenBaseLocalVar.BeginRateLimit();
+
+                        return apiResponseLocalVar;
+                    }
+                }
+            }
+            catch(Exception e)
+            {
+                OnErrorUploadFilesDefaultImplementation(e, "/pet/{petId}/uploadImages", uriBuilderLocalVar.Path, files, petId);
+                Events.ExecuteOnErrorUploadFiles(e);
+                throw;
+            }
+        }
+
+        /// <summary>
+        /// The <see cref="UploadFilesApiResponse"/>
+        /// </summary>
+        public partial class UploadFilesApiResponse : Org.OpenAPITools.Client.ApiResponse, IUploadFilesApiResponse
+        {
+            /// <summary>
+            /// The logger
+            /// </summary>
+            public ILogger<UploadFilesApiResponse> Logger { get; }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="rawContent"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, string rawContent, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, rawContent, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="contentStream"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, System.IO.Stream contentStream, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, contentStream, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            partial void OnCreated(global::System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage);
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public bool IsOk => 200 == (int)StatusCode;
+
+            /// <summary>
+            /// Deserializes the response if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public Org.OpenAPITools.Model.ApiResponse Ok()
+            {
+                // This logic may be modified with the AsModel.mustache template
+                return IsOk
+                    ? System.Text.Json.JsonSerializer.Deserialize<Org.OpenAPITools.Model.ApiResponse>(RawContent, _jsonSerializerOptions)
+                    : null;
+            }
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok and the deserialized response is not null
+            /// </summary>
+            /// <param name="result"></param>
+            /// <returns></returns>
+            public bool TryOk([NotNullWhen(true)]out Org.OpenAPITools.Model.ApiResponse result)
+            {
+                result = null;
+
+                try
+                {
+                    result = Ok();
+                } catch (Exception e)
+                {
+                    OnDeserializationErrorDefaultImplementation(e, (HttpStatusCode)200);
+                }
+
+                return result != null;
+            }
+
+            private void OnDeserializationErrorDefaultImplementation(Exception exception, HttpStatusCode httpStatusCode)
+            {
+                bool suppressDefaultLog = false;
+                OnDeserializationError(ref suppressDefaultLog, exception, httpStatusCode);
+                if (!suppressDefaultLog)
+                    Logger.LogError(exception, "An error occurred while deserializing the {code} response.", httpStatusCode);
+            }
+
+            partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/net8/Petstore/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net8/Petstore/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..6150dbcf4774
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net8/Petstore/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,40 @@
+// <auto-generated>
+/*
+ * OpenAPI Petstore
+ *
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net8/SourceGeneration/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net8/SourceGeneration/.openapi-generator/FILES
index ab28c754b4b1..a3e02b328e0a 100644
--- a/samples/client/petstore/csharp/generichost/net8/SourceGeneration/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net8/SourceGeneration/.openapi-generator/FILES
@@ -140,6 +140,7 @@ src/Org.OpenAPITools/Client/DateOnlyNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningToken.cs
diff --git a/samples/client/petstore/csharp/generichost/net8/SourceGeneration/api/openapi.yaml b/samples/client/petstore/csharp/generichost/net8/SourceGeneration/api/openapi.yaml
index d8106a5755fc..ca451f3fb832 100644
--- a/samples/client/petstore/csharp/generichost/net8/SourceGeneration/api/openapi.yaml
+++ b/samples/client/petstore/csharp/generichost/net8/SourceGeneration/api/openapi.yaml
@@ -331,6 +331,40 @@ paths:
       summary: uploads an image
       tags:
       - pet
+  /pet/{petId}/uploadImages:
+    post:
+      description: ""
+      operationId: uploadFiles
+      parameters:
+      - description: ID of pet to update
+        explode: false
+        in: path
+        name: petId
+        required: true
+        schema:
+          format: int64
+          type: integer
+        style: simple
+      requestBody:
+        content:
+          multipart/form-data:
+            schema:
+              $ref: "#/components/schemas/uploadFiles_request"
+        required: true
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ApiResponse"
+          description: successful operation
+      security:
+      - petstore_auth:
+        - write:pets
+        - read:pets
+      summary: uploads an images
+      tags:
+      - pet
   /store/inventory:
     get:
       description: Returns a map of status codes to quantities
@@ -2924,6 +2958,16 @@ components:
           format: binary
           type: string
       type: object
+    uploadFiles_request:
+      properties:
+        files:
+          items:
+            format: binary
+            type: string
+          type: array
+      required:
+      - files
+      type: object
     testEnumParameters_request:
       properties:
         enum_form_string_array:
diff --git a/samples/client/petstore/csharp/generichost/net8/SourceGeneration/docs/apis/PetApi.md b/samples/client/petstore/csharp/generichost/net8/SourceGeneration/docs/apis/PetApi.md
index 2826ea00f728..b42ee516b313 100644
--- a/samples/client/petstore/csharp/generichost/net8/SourceGeneration/docs/apis/PetApi.md
+++ b/samples/client/petstore/csharp/generichost/net8/SourceGeneration/docs/apis/PetApi.md
@@ -13,6 +13,7 @@ All URIs are relative to *http://petstore.swagger.io:80/v2*
 | [**UpdatePetWithForm**](PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data |
 | [**UploadFile**](PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image |
 | [**UploadFileWithRequiredFile**](PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required) |
+| [**UploadFiles**](PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images |
 
 <a id="addpet"></a>
 # **AddPet**
@@ -341,3 +342,38 @@ uploads an image (required)
 
 [[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
 
+<a id="uploadfiles"></a>
+# **UploadFiles**
+> ApiResponse UploadFiles (List<System.IO.Stream> files, long petId)
+
+uploads an images
+
+
+### Parameters
+
+| Name | Type | Description | Notes |
+|------|------|-------------|-------|
+| **files** | **List&lt;System.IO.Stream&gt;** |  |  |
+| **petId** | **long** | ID of pet to update |  |
+
+### Return type
+
+[**ApiResponse**](ApiResponse.md)
+
+### Authorization
+
+[petstore_auth](../README.md#petstore_auth)
+
+### HTTP request headers
+
+ - **Content-Type**: multipart/form-data
+ - **Accept**: application/json
+
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **200** | successful operation |  -  |
+
+[[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
+
diff --git a/samples/client/petstore/csharp/generichost/net8/SourceGeneration/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs b/samples/client/petstore/csharp/generichost/net8/SourceGeneration/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
index 406dbc964a6d..d207bb93dc69 100644
--- a/samples/client/petstore/csharp/generichost/net8/SourceGeneration/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/net8/SourceGeneration/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
@@ -196,7 +196,7 @@ public async Task TestEndpointParametersAsyncTest()
             string patternWithoutDelimiter = default!;
             byte[] varByte = default!;
             double varDouble = default!;
-            Client.Option<System.IO.Stream> binary = default!;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> binary = default!;
             Client.Option<string> callback = default!;
             Client.Option<DateOnly> date = default!;
             Client.Option<DateTime> dateTime = default!;
diff --git a/samples/client/petstore/csharp/generichost/net8/SourceGeneration/src/Org.OpenAPITools.Test/Api/PetApiTests.cs b/samples/client/petstore/csharp/generichost/net8/SourceGeneration/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
index 49e7b21b53c2..6bb1f953987c 100644
--- a/samples/client/petstore/csharp/generichost/net8/SourceGeneration/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/net8/SourceGeneration/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
@@ -137,7 +137,7 @@ public async Task UploadFileAsyncTest()
         {
             long petId = default!;
             Client.Option<string> additionalMetadata = default!;
-            Client.Option<System.IO.Stream> file = default!;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> file = default!;
             var response = await _instance.UploadFileAsync(petId, additionalMetadata, file);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
@@ -150,11 +150,24 @@ public async Task UploadFileAsyncTest()
         public async Task UploadFileWithRequiredFileAsyncTest()
         {
             long petId = default!;
-            System.IO.Stream requiredFile = default!;
+            Org.OpenAPITools.Client.FileParameter requiredFile = default!;
             Client.Option<string> additionalMetadata = default!;
             var response = await _instance.UploadFileWithRequiredFileAsync(petId, requiredFile, additionalMetadata);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
         }
+
+        /// <summary>
+        /// Test UploadFiles
+        /// </summary>
+        [Fact (Skip = "not implemented")]
+        public async Task UploadFilesAsyncTest()
+        {
+            List<Org.OpenAPITools.Client.FileParameter> files = default!;
+            long petId = default!;
+            var response = await _instance.UploadFilesAsync(files, petId);
+            var model = response.Ok();
+            Assert.IsType<ApiResponse>(model);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/net8/SourceGeneration/src/Org.OpenAPITools/Api/DefaultApi.cs b/samples/client/petstore/csharp/generichost/net8/SourceGeneration/src/Org.OpenAPITools/Api/DefaultApi.cs
index 2391c7e1ee03..46b798fe32ca 100644
--- a/samples/client/petstore/csharp/generichost/net8/SourceGeneration/src/Org.OpenAPITools/Api/DefaultApi.cs
+++ b/samples/client/petstore/csharp/generichost/net8/SourceGeneration/src/Org.OpenAPITools/Api/DefaultApi.cs
@@ -766,15 +766,12 @@ public async Task<IGetCountryApiResponse> GetCountryAsync(string country, System
                         ? "/country"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/country");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("country", ClientUtils.ParameterToString(country)));
 
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
-
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("country", ClientUtils.ParameterToString(country)));
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
 
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -782,11 +779,6 @@ public async Task<IGetCountryApiResponse> GetCountryAsync(string country, System
                         "application/x-www-form-urlencoded"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/net8/SourceGeneration/src/Org.OpenAPITools/Api/FakeApi.cs b/samples/client/petstore/csharp/generichost/net8/SourceGeneration/src/Org.OpenAPITools/Api/FakeApi.cs
index 262a94ef2520..54a1c8c85360 100644
--- a/samples/client/petstore/csharp/generichost/net8/SourceGeneration/src/Org.OpenAPITools/Api/FakeApi.cs
+++ b/samples/client/petstore/csharp/generichost/net8/SourceGeneration/src/Org.OpenAPITools/Api/FakeApi.cs
@@ -332,7 +332,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -356,7 +356,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>?&gt;</returns>
-        Task<ITestEndpointParametersApiResponse?> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse?> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// To test enum parameters
@@ -4082,7 +4082,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<System.IO.Stream> binary, ref Option<string> callback, ref Option<DateOnly> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
+        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<Org.OpenAPITools.Client.FileParameter> binary, ref Option<string> callback, ref Option<DateOnly> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
 
         /// <summary>
         /// Validates the request parameters
@@ -4094,7 +4094,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="password"></param>
         /// <param name="varString"></param>
         /// <returns></returns>
-        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<System.IO.Stream> binary, Option<string> callback, Option<string> password, Option<string> varString)
+        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<string> password, Option<string> varString)
         {
             if (patternWithoutDelimiter == null)
                 throw new ArgumentNullException(nameof(patternWithoutDelimiter));
@@ -4133,7 +4133,7 @@ private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLog = false;
             AfterTestEndpointParameters(ref suppressDefaultLog, apiResponseLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4160,7 +4160,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -4182,7 +4182,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorTestEndpointParameters(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4211,7 +4211,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트  Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -4232,7 +4232,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse?> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse?> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -4264,7 +4264,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -4283,51 +4283,48 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         ? "/fake"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("number", ClientUtils.ParameterToString(number)));
 
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("pattern_without_delimiter", ClientUtils.ParameterToString(patternWithoutDelimiter)));
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("byte", ClientUtils.ParameterToString(varByte)));
 
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("number", ClientUtils.ParameterToString(number)));
-
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("pattern_without_delimiter", ClientUtils.ParameterToString(patternWithoutDelimiter)));
-
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("byte", ClientUtils.ParameterToString(varByte)));
-
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("double", ClientUtils.ParameterToString(varDouble)));
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("double", ClientUtils.ParameterToString(varDouble)));
 
                     if (binary.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(binary.Value));
+                        throw new NotSupportedException("File parameters cannot be sent with application/x-www-form-urlencoded. Change the operation's content type to multipart/form-data.");
 
                     if (callback.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("callback", ClientUtils.ParameterToString(callback.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("callback", ClientUtils.ParameterToString(callback.Value)));
 
                     if (date.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("date", ClientUtils.ParameterToString(date.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("date", ClientUtils.ParameterToString(date.Value)));
 
                     if (dateTime.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("dateTime", ClientUtils.ParameterToString(dateTime.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("dateTime", ClientUtils.ParameterToString(dateTime.Value)));
 
                     if (int32.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("int32", ClientUtils.ParameterToString(int32.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("int32", ClientUtils.ParameterToString(int32.Value)));
 
                     if (int64.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("int64", ClientUtils.ParameterToString(int64.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("int64", ClientUtils.ParameterToString(int64.Value)));
 
                     if (integer.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("integer", ClientUtils.ParameterToString(integer.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("integer", ClientUtils.ParameterToString(integer.Value)));
 
                     if (password.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("password", ClientUtils.ParameterToString(password.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("password", ClientUtils.ParameterToString(password.Value)));
 
                     if (varFloat.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("float", ClientUtils.ParameterToString(varFloat.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("float", ClientUtils.ParameterToString(varFloat.Value)));
 
                     if (varString.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("string", ClientUtils.ParameterToString(varString.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("string", ClientUtils.ParameterToString(varString.Value)));
+
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -4342,11 +4339,6 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         "application/x-www-form-urlencoded"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -4639,17 +4631,16 @@ public async Task<ITestEnumParametersApiResponse> TestEnumParametersAsync(Option
                     if (enumHeaderStringArray.IsSet)
                         httpRequestMessageLocalVar.Headers.Add("enum_header_string_array", ClientUtils.ParameterToString(enumHeaderStringArray.Value));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
-
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (enumFormString.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("enum_form_string", ClientUtils.ParameterToString(enumFormString.Value)));
+                    if (enumFormString.IsSet)
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("enum_form_string", ClientUtils.ParameterToString(enumFormString.Value)));
 
                     if (enumFormStringArray.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("enum_form_string_array", ClientUtils.ParameterToString(enumFormStringArray.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("enum_form_string_array", ClientUtils.ParameterToString(enumFormStringArray.Value)));
+
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
 
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -4657,11 +4648,6 @@ public async Task<ITestEnumParametersApiResponse> TestEnumParametersAsync(Option
                         "application/x-www-form-urlencoded"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Get;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -5548,17 +5534,14 @@ public async Task<ITestJsonFormDataApiResponse> TestJsonFormDataAsync(string par
                         ? "/fake/jsonFormData"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/jsonFormData");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("param", ClientUtils.ParameterToString(param)));
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("param2", ClientUtils.ParameterToString(param2)));
 
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("param", ClientUtils.ParameterToString(param)));
-
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("param2", ClientUtils.ParameterToString(param2)));
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
 
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -5566,11 +5549,6 @@ public async Task<ITestJsonFormDataApiResponse> TestJsonFormDataAsync(string par
                         "application/x-www-form-urlencoded"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Get;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/net8/SourceGeneration/src/Org.OpenAPITools/Api/PetApi.cs b/samples/client/petstore/csharp/generichost/net8/SourceGeneration/src/Org.OpenAPITools/Api/PetApi.cs
index 2d7e4dab0b84..c5de9cd55ad1 100644
--- a/samples/client/petstore/csharp/generichost/net8/SourceGeneration/src/Org.OpenAPITools/Api/PetApi.cs
+++ b/samples/client/petstore/csharp/generichost/net8/SourceGeneration/src/Org.OpenAPITools/Api/PetApi.cs
@@ -218,7 +218,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image
@@ -231,7 +231,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>?&gt;</returns>
-        Task<IUploadFileApiResponse?> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse?> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -245,7 +245,7 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -258,7 +258,32 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>?&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse?> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse?> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>?&gt;</returns>
+        Task<IUploadFilesApiResponse?> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
     }
 
     /// <summary>
@@ -417,6 +442,18 @@ public interface IUploadFileWithRequiredFileApiResponse : Org.OpenAPITools.Clien
         bool IsOk { get; }
     }
 
+    /// <summary>
+    /// The <see cref="IUploadFilesApiResponse"/>
+    /// </summary>
+    public interface IUploadFilesApiResponse : Org.OpenAPITools.Client.IApiResponse, IOk<Org.OpenAPITools.Model.ApiResponse?>
+    {
+        /// <summary>
+        /// Returns true if the response is 200 Ok
+        /// </summary>
+        /// <returns></returns>
+        bool IsOk { get; }
+    }
+
     /// <summary>
     /// Represents a collection of functions to interact with the API endpoints
     /// </summary>
@@ -601,6 +638,26 @@ internal void ExecuteOnErrorUploadFileWithRequiredFile(Exception exception)
         {
             OnErrorUploadFileWithRequiredFile?.Invoke(this, new ExceptionEventArgs(exception));
         }
+
+        /// <summary>
+        /// The event raised after the server response
+        /// </summary>
+        public event EventHandler<ApiResponseEventArgs>? OnUploadFiles;
+
+        /// <summary>
+        /// The event raised after an error querying the server
+        /// </summary>
+        public event EventHandler<ExceptionEventArgs>? OnErrorUploadFiles;
+
+        internal void ExecuteOnUploadFiles(PetApi.UploadFilesApiResponse apiResponse)
+        {
+            OnUploadFiles?.Invoke(this, new ApiResponseEventArgs(apiResponse));
+        }
+
+        internal void ExecuteOnErrorUploadFiles(Exception exception)
+        {
+            OnErrorUploadFiles?.Invoke(this, new ExceptionEventArgs(exception));
+        }
     }
 
     /// <summary>
@@ -2332,17 +2389,16 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (name.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("name", ClientUtils.ParameterToString(name.Value)));
+                    if (name.IsSet)
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("name", ClientUtils.ParameterToString(name.Value)));
 
                     if (status.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("status", ClientUtils.ParameterToString(status.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("status", ClientUtils.ParameterToString(status.Value)));
+
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -2357,11 +2413,6 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         "application/x-www-form-urlencoded"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -2461,7 +2512,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<System.IO.Stream> file);
+        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Validates the request parameters
@@ -2469,7 +2520,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
         /// <returns></returns>
-        private void ValidateUploadFile(Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void ValidateUploadFile(Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             if (additionalMetadata.IsSet && additionalMetadata.Value == null)
                 throw new ArgumentNullException(nameof(additionalMetadata));
@@ -2485,7 +2536,7 @@ private void ValidateUploadFile(Option<string> additionalMetadata, Option<System
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLog = false;
             AfterUploadFile(ref suppressDefaultLog, apiResponseLocalVar, petId, additionalMetadata, file);
@@ -2501,7 +2552,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2512,7 +2563,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, additionalMetadata, file);
@@ -2530,7 +2581,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// uploads an image 
@@ -2540,7 +2591,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse?> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse?> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2561,7 +2612,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2581,17 +2632,23 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImage");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (additionalMetadata.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
+                    if (additionalMetadata.IsSet)
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
 
                     if (file.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(file.Value));
+                    {
+                        var streamContentLocalVar = new StreamContent(file.Value.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "file", file.Value.FileName ?? "file");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -2606,11 +2663,6 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         "multipart/form-data"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json"
                     };
@@ -2751,7 +2803,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFileWithRequiredFile(ref long petId, ref System.IO.Stream requiredFile, ref Option<string> additionalMetadata);
+        partial void FormatUploadFileWithRequiredFile(ref long petId, ref Org.OpenAPITools.Client.FileParameter requiredFile, ref Option<string> additionalMetadata);
 
         /// <summary>
         /// Validates the request parameters
@@ -2759,7 +2811,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
         /// <returns></returns>
-        private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void ValidateUploadFileWithRequiredFile(Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             if (requiredFile == null)
                 throw new ArgumentNullException(nameof(requiredFile));
@@ -2775,7 +2827,7 @@ private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, O
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLog = false;
             AfterUploadFileWithRequiredFile(ref suppressDefaultLog, apiResponseLocalVar, petId, requiredFile, additionalMetadata);
@@ -2791,7 +2843,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2802,7 +2854,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFileWithRequiredFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, requiredFile, additionalMetadata);
@@ -2820,7 +2872,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// uploads an image (required) 
@@ -2830,7 +2882,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse?> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse?> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2851,7 +2903,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2871,16 +2923,22 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/{petId}/uploadImageWithRequiredFile");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    multipartContentLocalVar.Add(new StreamContent(requiredFile));
+                    {
+                        var streamContentLocalVar = new StreamContent(requiredFile.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "requiredFile", requiredFile.FileName ?? "requiredFile");
+                    }
 
                     if (additionalMetadata.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -2895,11 +2953,6 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         "multipart/form-data"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json",
                         "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
@@ -3040,5 +3093,283 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
 
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
+
+        partial void FormatUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files, ref long petId);
+
+        /// <summary>
+        /// Validates the request parameters
+        /// </summary>
+        /// <param name="files"></param>
+        /// <returns></returns>
+        private void ValidateUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files)
+        {
+            if (files == null)
+                throw new ArgumentNullException(nameof(files));
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void AfterUploadFilesDefaultImplementation(IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLog = false;
+            AfterUploadFiles(ref suppressDefaultLog, apiResponseLocalVar, files, petId);
+            if (!suppressDefaultLog)
+                Logger.LogInformation("{0,-9} | {1} | {2}", (apiResponseLocalVar.DownloadedAt - apiResponseLocalVar.RequestedAt).TotalSeconds, apiResponseLocalVar.StatusCode, apiResponseLocalVar.Path);
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="suppressDefaultLog"></param>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void AfterUploadFiles(ref bool suppressDefaultLog, IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// Logs exceptions that occur while retrieving the server response
+        /// </summary>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void OnErrorUploadFilesDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLogLocalVar = false;
+            OnErrorUploadFiles(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, files, petId);
+            if (!suppressDefaultLogLocalVar)
+                Logger.LogError(exceptionLocalVar, "An error occurred while sending the request to the server.");
+        }
+
+        /// <summary>
+        /// A partial method that gives developers a way to provide customized exception handling
+        /// </summary>
+        /// <param name="suppressDefaultLogLocalVar"></param>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void OnErrorUploadFiles(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse?> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            try
+            {
+                return await UploadFilesAsync(files, petId, cancellationToken).ConfigureAwait(false);
+            }
+            catch (Exception)
+            {
+                return null;
+            }
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            UriBuilder uriBuilderLocalVar = new UriBuilder();
+
+            try
+            {
+                ValidateUploadFiles(files);
+
+                FormatUploadFiles(files, ref petId);
+
+                using (HttpRequestMessage httpRequestMessageLocalVar = new HttpRequestMessage())
+                {
+                    uriBuilderLocalVar.Host = HttpClient.BaseAddress!.Host;
+                    uriBuilderLocalVar.Port = HttpClient.BaseAddress.Port;
+                    uriBuilderLocalVar.Scheme = HttpClient.BaseAddress.Scheme;
+                    uriBuilderLocalVar.Path = HttpClient.BaseAddress.AbsolutePath == "/"
+                        ? "/pet/{petId}/uploadImages"
+                        : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImages");
+                    uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
+
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
+
+                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
+
+                    foreach (Org.OpenAPITools.Client.FileParameter fileParameterLocalVar in files)
+                    {
+                        var streamContentLocalVar = new StreamContent(fileParameterLocalVar.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "files", fileParameterLocalVar.FileName ?? "files");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
+
+                    List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
+                    httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
+
+                    OAuthToken oauthTokenLocalVar1 = (OAuthToken) await OauthTokenProvider.GetAsync(cancellation: cancellationToken).ConfigureAwait(false);
+
+                    tokenBaseLocalVars.Add(oauthTokenLocalVar1);
+
+                    oauthTokenLocalVar1.UseInHeader(httpRequestMessageLocalVar, "");
+
+                    string[] contentTypes = new string[] {
+                        "multipart/form-data"
+                    };
+
+                    string[] acceptLocalVars = new string[] {
+                        "application/json"
+                    };
+
+                    IEnumerable<MediaTypeWithQualityHeaderValue> acceptHeaderValuesLocalVar = ClientUtils.SelectHeaderAcceptArray(acceptLocalVars);
+
+                    foreach (var acceptLocalVar in acceptHeaderValuesLocalVar)
+                        httpRequestMessageLocalVar.Headers.Accept.Add(acceptLocalVar);
+
+                    httpRequestMessageLocalVar.Method = HttpMethod.Post;
+
+                    DateTime requestedAtLocalVar = DateTime.UtcNow;
+
+                    using (HttpResponseMessage httpResponseMessageLocalVar = await HttpClient.SendAsync(httpRequestMessageLocalVar, cancellationToken).ConfigureAwait(false))
+                    {
+                        ILogger<UploadFilesApiResponse> apiResponseLoggerLocalVar = LoggerFactory.CreateLogger<UploadFilesApiResponse>();
+                        UploadFilesApiResponse apiResponseLocalVar;
+
+                        switch ((int)httpResponseMessageLocalVar.StatusCode) {
+                            default: {
+                                string responseContentLocalVar = await httpResponseMessageLocalVar.Content.ReadAsStringAsync(cancellationToken).ConfigureAwait(false);
+                                apiResponseLocalVar = new(apiResponseLoggerLocalVar, httpRequestMessageLocalVar, httpResponseMessageLocalVar, responseContentLocalVar, "/pet/{petId}/uploadImages", requestedAtLocalVar, _jsonSerializerOptions);
+
+                                break;
+                            }
+                        }
+
+                        AfterUploadFilesDefaultImplementation(apiResponseLocalVar, files, petId);
+
+                        Events.ExecuteOnUploadFiles(apiResponseLocalVar);
+
+                        if (apiResponseLocalVar.StatusCode == (HttpStatusCode) 429)
+                            foreach(TokenBase tokenBaseLocalVar in tokenBaseLocalVars)
+                                tokenBaseLocalVar.BeginRateLimit();
+
+                        return apiResponseLocalVar;
+                    }
+                }
+            }
+            catch(Exception e)
+            {
+                OnErrorUploadFilesDefaultImplementation(e, "/pet/{petId}/uploadImages", uriBuilderLocalVar.Path, files, petId);
+                Events.ExecuteOnErrorUploadFiles(e);
+                throw;
+            }
+        }
+
+        /// <summary>
+        /// The <see cref="UploadFilesApiResponse"/>
+        /// </summary>
+        public partial class UploadFilesApiResponse : Org.OpenAPITools.Client.ApiResponse, IUploadFilesApiResponse
+        {
+            /// <summary>
+            /// The logger
+            /// </summary>
+            public ILogger<UploadFilesApiResponse> Logger { get; }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="rawContent"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, string rawContent, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, rawContent, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="contentStream"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, System.IO.Stream contentStream, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, contentStream, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            partial void OnCreated(global::System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage);
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public bool IsOk => 200 == (int)StatusCode;
+
+            /// <summary>
+            /// Deserializes the response if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public Org.OpenAPITools.Model.ApiResponse? Ok()
+            {
+                // This logic may be modified with the AsModel.mustache template
+                return IsOk
+                    ? System.Text.Json.JsonSerializer.Deserialize<Org.OpenAPITools.Model.ApiResponse>(RawContent, _jsonSerializerOptions)
+                    : null;
+            }
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok and the deserialized response is not null
+            /// </summary>
+            /// <param name="result"></param>
+            /// <returns></returns>
+            public bool TryOk([NotNullWhen(true)]out Org.OpenAPITools.Model.ApiResponse? result)
+            {
+                result = null;
+
+                try
+                {
+                    result = Ok();
+                } catch (Exception e)
+                {
+                    OnDeserializationErrorDefaultImplementation(e, (HttpStatusCode)200);
+                }
+
+                return result != null;
+            }
+
+            private void OnDeserializationErrorDefaultImplementation(Exception exception, HttpStatusCode httpStatusCode)
+            {
+                bool suppressDefaultLog = false;
+                OnDeserializationError(ref suppressDefaultLog, exception, httpStatusCode);
+                if (!suppressDefaultLog)
+                    Logger.LogError(exception, "An error occurred while deserializing the {code} response.", httpStatusCode);
+            }
+
+            partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/net8/SourceGeneration/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net8/SourceGeneration/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..77779fe7d75a
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net8/SourceGeneration/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,42 @@
+// <auto-generated>
+/*
+ * OpenAPI Petstore
+ *
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+#nullable enable
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string? FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string? fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net8/UseDateTimeForDate/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net8/UseDateTimeForDate/.openapi-generator/FILES
index 5abbcf46f35c..e28da391730f 100644
--- a/samples/client/petstore/csharp/generichost/net8/UseDateTimeForDate/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net8/UseDateTimeForDate/.openapi-generator/FILES
@@ -21,6 +21,7 @@ src/Org.OpenAPITools/Client/CookieContainer.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/JsonSerializerOptionsProvider.cs
 src/Org.OpenAPITools/Client/Option.cs
diff --git a/samples/client/petstore/csharp/generichost/net8/UseDateTimeForDate/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net8/UseDateTimeForDate/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..11da1d925144
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net8/UseDateTimeForDate/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,42 @@
+// <auto-generated>
+/*
+ * OpenAPI Dates
+ *
+ * Thic spec contains endpoints with dates in different formats
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+#nullable enable
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string? FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string? fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net9/AllOf/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net9/AllOf/.openapi-generator/FILES
index b9ab612bd8b5..46a8286dea29 100644
--- a/samples/client/petstore/csharp/generichost/net9/AllOf/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net9/AllOf/.openapi-generator/FILES
@@ -25,6 +25,7 @@ src/Org.OpenAPITools/Client/DateOnlyNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/JsonSerializerOptionsProvider.cs
 src/Org.OpenAPITools/Client/Option.cs
diff --git a/samples/client/petstore/csharp/generichost/net9/AllOf/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net9/AllOf/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..1913a3a0f2d9
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net9/AllOf/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,42 @@
+// <auto-generated>
+/*
+ * Example
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+#nullable enable
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string? FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string? fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net9/AnyOf/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net9/AnyOf/.openapi-generator/FILES
index dc42a5d47091..072cc8408121 100644
--- a/samples/client/petstore/csharp/generichost/net9/AnyOf/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net9/AnyOf/.openapi-generator/FILES
@@ -25,6 +25,7 @@ src/Org.OpenAPITools/Client/DateOnlyNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/JsonSerializerOptionsProvider.cs
 src/Org.OpenAPITools/Client/Option.cs
diff --git a/samples/client/petstore/csharp/generichost/net9/AnyOf/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net9/AnyOf/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..e629f4afdaec
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net9/AnyOf/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,42 @@
+// <auto-generated>
+/*
+ * fruity
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * The version of the OpenAPI document: 0.0.1
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+#nullable enable
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string? FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string? fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net9/AnyOfNoCompare/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net9/AnyOfNoCompare/.openapi-generator/FILES
index dc42a5d47091..072cc8408121 100644
--- a/samples/client/petstore/csharp/generichost/net9/AnyOfNoCompare/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net9/AnyOfNoCompare/.openapi-generator/FILES
@@ -25,6 +25,7 @@ src/Org.OpenAPITools/Client/DateOnlyNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/JsonSerializerOptionsProvider.cs
 src/Org.OpenAPITools/Client/Option.cs
diff --git a/samples/client/petstore/csharp/generichost/net9/AnyOfNoCompare/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net9/AnyOfNoCompare/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..e629f4afdaec
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net9/AnyOfNoCompare/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,42 @@
+// <auto-generated>
+/*
+ * fruity
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * The version of the OpenAPI document: 0.0.1
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+#nullable enable
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string? FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string? fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net9/FormModels/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net9/FormModels/.openapi-generator/FILES
index a9823b3075fd..737d53400248 100644
--- a/samples/client/petstore/csharp/generichost/net9/FormModels/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net9/FormModels/.openapi-generator/FILES
@@ -165,6 +165,7 @@ src/Org.OpenAPITools/Client/DateOnlyNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningToken.cs
diff --git a/samples/client/petstore/csharp/generichost/net9/FormModels/api/openapi.yaml b/samples/client/petstore/csharp/generichost/net9/FormModels/api/openapi.yaml
index a9ab8dd51c13..7017affc0b9c 100644
--- a/samples/client/petstore/csharp/generichost/net9/FormModels/api/openapi.yaml
+++ b/samples/client/petstore/csharp/generichost/net9/FormModels/api/openapi.yaml
@@ -326,6 +326,40 @@ paths:
       summary: uploads an image
       tags:
       - pet
+  /pet/{petId}/uploadImages:
+    post:
+      description: ""
+      operationId: uploadFiles
+      parameters:
+      - description: ID of pet to update
+        explode: false
+        in: path
+        name: petId
+        required: true
+        schema:
+          format: int64
+          type: integer
+        style: simple
+      requestBody:
+        content:
+          multipart/form-data:
+            schema:
+              $ref: "#/components/schemas/uploadFiles_request"
+        required: true
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ApiResponse"
+          description: successful operation
+      security:
+      - petstore_auth:
+        - write:pets
+        - read:pets
+      summary: uploads an images
+      tags:
+      - pet
   /store/inventory:
     get:
       description: Returns a map of status codes to quantities
@@ -2748,6 +2782,16 @@ components:
           format: binary
           type: string
       type: object
+    uploadFiles_request:
+      properties:
+        files:
+          items:
+            format: binary
+            type: string
+          type: array
+      required:
+      - files
+      type: object
     testEnumParameters_request_enum_form_string_array_inner:
       default: $
       enum:
diff --git a/samples/client/petstore/csharp/generichost/net9/FormModels/docs/apis/PetApi.md b/samples/client/petstore/csharp/generichost/net9/FormModels/docs/apis/PetApi.md
index e32c1e31e089..59d4ef8e6df0 100644
--- a/samples/client/petstore/csharp/generichost/net9/FormModels/docs/apis/PetApi.md
+++ b/samples/client/petstore/csharp/generichost/net9/FormModels/docs/apis/PetApi.md
@@ -13,6 +13,7 @@ All URIs are relative to *http://petstore.swagger.io:80/v2*
 | [**UpdatePetWithForm**](PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data |
 | [**UploadFile**](PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image |
 | [**UploadFileWithRequiredFile**](PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required) |
+| [**UploadFiles**](PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images |
 
 <a id="addpet"></a>
 # **AddPet**
@@ -341,3 +342,38 @@ uploads an image (required)
 
 [[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
 
+<a id="uploadfiles"></a>
+# **UploadFiles**
+> ApiResponse UploadFiles (List<System.IO.Stream> files, long petId)
+
+uploads an images
+
+
+### Parameters
+
+| Name | Type | Description | Notes |
+|------|------|-------------|-------|
+| **files** | **List&lt;System.IO.Stream&gt;** |  |  |
+| **petId** | **long** | ID of pet to update |  |
+
+### Return type
+
+[**ApiResponse**](ApiResponse.md)
+
+### Authorization
+
+[petstore_auth](../README.md#petstore_auth)
+
+### HTTP request headers
+
+ - **Content-Type**: multipart/form-data
+ - **Accept**: application/json
+
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **200** | successful operation |  -  |
+
+[[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
+
diff --git a/samples/client/petstore/csharp/generichost/net9/FormModels/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs b/samples/client/petstore/csharp/generichost/net9/FormModels/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
index 495d785314c5..1924842cdbef 100644
--- a/samples/client/petstore/csharp/generichost/net9/FormModels/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/net9/FormModels/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
@@ -196,7 +196,7 @@ public async Task TestEndpointParametersAsyncTest()
             string patternWithoutDelimiter = default;
             byte[] varByte = default;
             double varDouble = default;
-            Client.Option<System.IO.Stream> binary = default;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> binary = default;
             Client.Option<string> callback = default;
             Client.Option<DateOnly> date = default;
             Client.Option<DateTime> dateTime = default;
diff --git a/samples/client/petstore/csharp/generichost/net9/FormModels/src/Org.OpenAPITools.Test/Api/PetApiTests.cs b/samples/client/petstore/csharp/generichost/net9/FormModels/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
index 1f1d7f6c4576..a4aa8f3e245d 100644
--- a/samples/client/petstore/csharp/generichost/net9/FormModels/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/net9/FormModels/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
@@ -137,7 +137,7 @@ public async Task UploadFileAsyncTest()
         {
             long petId = default;
             Client.Option<string> additionalMetadata = default;
-            Client.Option<System.IO.Stream> file = default;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> file = default;
             var response = await _instance.UploadFileAsync(petId, additionalMetadata, file);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
@@ -150,11 +150,24 @@ public async Task UploadFileAsyncTest()
         public async Task UploadFileWithRequiredFileAsyncTest()
         {
             long petId = default;
-            System.IO.Stream requiredFile = default;
+            Org.OpenAPITools.Client.FileParameter requiredFile = default;
             Client.Option<string> additionalMetadata = default;
             var response = await _instance.UploadFileWithRequiredFileAsync(petId, requiredFile, additionalMetadata);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
         }
+
+        /// <summary>
+        /// Test UploadFiles
+        /// </summary>
+        [Fact (Skip = "not implemented")]
+        public async Task UploadFilesAsyncTest()
+        {
+            List<Org.OpenAPITools.Client.FileParameter> files = default;
+            long petId = default;
+            var response = await _instance.UploadFilesAsync(files, petId);
+            var model = response.Ok();
+            Assert.IsType<ApiResponse>(model);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/net9/FormModels/src/Org.OpenAPITools/Api/DefaultApi.cs b/samples/client/petstore/csharp/generichost/net9/FormModels/src/Org.OpenAPITools/Api/DefaultApi.cs
index 3c26a27185e6..44d52e7e1090 100644
--- a/samples/client/petstore/csharp/generichost/net9/FormModels/src/Org.OpenAPITools/Api/DefaultApi.cs
+++ b/samples/client/petstore/csharp/generichost/net9/FormModels/src/Org.OpenAPITools/Api/DefaultApi.cs
@@ -764,27 +764,19 @@ public async Task<IGetCountryApiResponse> GetCountryAsync(string country, System
                         ? "/country"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/country");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("country", ClientUtils.ParameterToString(country)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/net9/FormModels/src/Org.OpenAPITools/Api/FakeApi.cs b/samples/client/petstore/csharp/generichost/net9/FormModels/src/Org.OpenAPITools/Api/FakeApi.cs
index 2a332dbf1eb9..0070617289e6 100644
--- a/samples/client/petstore/csharp/generichost/net9/FormModels/src/Org.OpenAPITools/Api/FakeApi.cs
+++ b/samples/client/petstore/csharp/generichost/net9/FormModels/src/Org.OpenAPITools/Api/FakeApi.cs
@@ -330,7 +330,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -354,7 +354,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// To test enum parameters
@@ -4080,7 +4080,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<System.IO.Stream> binary, ref Option<string> callback, ref Option<DateOnly> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
+        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<Org.OpenAPITools.Client.FileParameter> binary, ref Option<string> callback, ref Option<DateOnly> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
 
         /// <summary>
         /// Validates the request parameters
@@ -4092,7 +4092,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="password"></param>
         /// <param name="varString"></param>
         /// <returns></returns>
-        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<System.IO.Stream> binary, Option<string> callback, Option<string> password, Option<string> varString)
+        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<string> password, Option<string> varString)
         {
             if (patternWithoutDelimiter == null)
                 throw new ArgumentNullException(nameof(patternWithoutDelimiter));
@@ -4131,7 +4131,7 @@ private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLog = false;
             AfterTestEndpointParameters(ref suppressDefaultLog, apiResponseLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4158,7 +4158,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -4180,7 +4180,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorTestEndpointParameters(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4209,7 +4209,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트  Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -4230,7 +4230,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -4262,7 +4262,7 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDe
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -4281,14 +4281,8 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         ? "/fake"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("number", ClientUtils.ParameterToString(number)));
 
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("pattern_without_delimiter", ClientUtils.ParameterToString(patternWithoutDelimiter)));
@@ -4298,7 +4292,7 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("double", ClientUtils.ParameterToString(varDouble)));
 
                     if (binary.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(binary.Value));
+                        throw new NotSupportedException("File parameters cannot be sent with application/x-www-form-urlencoded. Change the operation's content type to multipart/form-data.");
 
                     if (callback.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("callback", ClientUtils.ParameterToString(callback.Value)));
@@ -4327,6 +4321,9 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                     if (varString.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("string", ClientUtils.ParameterToString(varString.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -4340,11 +4337,6 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -4625,29 +4617,23 @@ public async Task<ITestEnumParametersApiResponse> TestEnumParametersAsync(Option
                     if (enumHeaderStringArray.IsSet)
                         httpRequestMessageLocalVar.Headers.Add("enum_header_string_array", ClientUtils.ParameterToString(enumHeaderStringArray.Value));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (enumFormString.IsSet)
+                    if (enumFormString.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("enum_form_string", ClientUtils.ParameterToString(enumFormString.Value)));
 
                     if (enumFormStringArray.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("enum_form_string_array", ClientUtils.ParameterToString(enumFormStringArray.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Get;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -5534,29 +5520,21 @@ public async Task<ITestJsonFormDataApiResponse> TestJsonFormDataAsync(string par
                         ? "/fake/jsonFormData"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/jsonFormData");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("param", ClientUtils.ParameterToString(param)));
 
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("param2", ClientUtils.ParameterToString(param2)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Get;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/net9/FormModels/src/Org.OpenAPITools/Api/PetApi.cs b/samples/client/petstore/csharp/generichost/net9/FormModels/src/Org.OpenAPITools/Api/PetApi.cs
index d07d16c30828..fd403446d9a6 100644
--- a/samples/client/petstore/csharp/generichost/net9/FormModels/src/Org.OpenAPITools/Api/PetApi.cs
+++ b/samples/client/petstore/csharp/generichost/net9/FormModels/src/Org.OpenAPITools/Api/PetApi.cs
@@ -216,7 +216,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image
@@ -229,7 +229,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -243,7 +243,7 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -256,7 +256,32 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        Task<IUploadFilesApiResponse> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
     }
 
     /// <summary>
@@ -415,6 +440,18 @@ public interface IUploadFileWithRequiredFileApiResponse : Org.OpenAPITools.Clien
         bool IsOk { get; }
     }
 
+    /// <summary>
+    /// The <see cref="IUploadFilesApiResponse"/>
+    /// </summary>
+    public interface IUploadFilesApiResponse : Org.OpenAPITools.Client.IApiResponse, IOk<Org.OpenAPITools.Model.ApiResponse>
+    {
+        /// <summary>
+        /// Returns true if the response is 200 Ok
+        /// </summary>
+        /// <returns></returns>
+        bool IsOk { get; }
+    }
+
     /// <summary>
     /// Represents a collection of functions to interact with the API endpoints
     /// </summary>
@@ -599,6 +636,26 @@ internal void ExecuteOnErrorUploadFileWithRequiredFile(Exception exception)
         {
             OnErrorUploadFileWithRequiredFile?.Invoke(this, new ExceptionEventArgs(exception));
         }
+
+        /// <summary>
+        /// The event raised after the server response
+        /// </summary>
+        public event EventHandler<ApiResponseEventArgs> OnUploadFiles;
+
+        /// <summary>
+        /// The event raised after an error querying the server
+        /// </summary>
+        public event EventHandler<ExceptionEventArgs> OnErrorUploadFiles;
+
+        internal void ExecuteOnUploadFiles(PetApi.UploadFilesApiResponse apiResponse)
+        {
+            OnUploadFiles?.Invoke(this, new ApiResponseEventArgs(apiResponse));
+        }
+
+        internal void ExecuteOnErrorUploadFiles(Exception exception)
+        {
+            OnErrorUploadFiles?.Invoke(this, new ExceptionEventArgs(exception));
+        }
     }
 
     /// <summary>
@@ -2330,18 +2387,17 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (name.IsSet)
+                    if (name.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("name", ClientUtils.ParameterToString(name.Value)));
 
                     if (status.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("status", ClientUtils.ParameterToString(status.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -2355,11 +2411,6 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -2459,7 +2510,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<System.IO.Stream> file);
+        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Validates the request parameters
@@ -2467,7 +2518,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
         /// <returns></returns>
-        private void ValidateUploadFile(Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void ValidateUploadFile(Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             if (additionalMetadata.IsSet && additionalMetadata.Value == null)
                 throw new ArgumentNullException(nameof(additionalMetadata));
@@ -2483,7 +2534,7 @@ private void ValidateUploadFile(Option<string> additionalMetadata, Option<System
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLog = false;
             AfterUploadFile(ref suppressDefaultLog, apiResponseLocalVar, petId, additionalMetadata, file);
@@ -2499,7 +2550,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2510,7 +2561,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, additionalMetadata, file);
@@ -2528,7 +2579,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// uploads an image 
@@ -2538,7 +2589,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2559,7 +2610,7 @@ public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, O
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2579,17 +2630,23 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImage");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (additionalMetadata.IsSet)
+                    if (additionalMetadata.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
 
                     if (file.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(file.Value));
+                    {
+                        var streamContentLocalVar = new StreamContent(file.Value.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "file", file.Value.FileName ?? "file");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -2604,11 +2661,6 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         "multipart/form-data"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json"
                     };
@@ -2749,7 +2801,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFileWithRequiredFile(ref long petId, ref System.IO.Stream requiredFile, ref Option<string> additionalMetadata);
+        partial void FormatUploadFileWithRequiredFile(ref long petId, ref Org.OpenAPITools.Client.FileParameter requiredFile, ref Option<string> additionalMetadata);
 
         /// <summary>
         /// Validates the request parameters
@@ -2757,7 +2809,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
         /// <returns></returns>
-        private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void ValidateUploadFileWithRequiredFile(Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             if (requiredFile == null)
                 throw new ArgumentNullException(nameof(requiredFile));
@@ -2773,7 +2825,7 @@ private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, O
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLog = false;
             AfterUploadFileWithRequiredFile(ref suppressDefaultLog, apiResponseLocalVar, petId, requiredFile, additionalMetadata);
@@ -2789,7 +2841,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2800,7 +2852,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFileWithRequiredFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, requiredFile, additionalMetadata);
@@ -2818,7 +2870,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// uploads an image (required) 
@@ -2828,7 +2880,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2849,7 +2901,7 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2869,17 +2921,23 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/{petId}/uploadImageWithRequiredFile");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    multipartContentLocalVar.Add(new StreamContent(requiredFile));
+                    {
+                        var streamContentLocalVar = new StreamContent(requiredFile.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "requiredFile", requiredFile.FileName ?? "requiredFile");
+                    }
 
                     if (additionalMetadata.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
 
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -2893,11 +2951,6 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         "multipart/form-data"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json",
                         "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
@@ -3038,5 +3091,283 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
 
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
+
+        partial void FormatUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files, ref long petId);
+
+        /// <summary>
+        /// Validates the request parameters
+        /// </summary>
+        /// <param name="files"></param>
+        /// <returns></returns>
+        private void ValidateUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files)
+        {
+            if (files == null)
+                throw new ArgumentNullException(nameof(files));
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void AfterUploadFilesDefaultImplementation(IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLog = false;
+            AfterUploadFiles(ref suppressDefaultLog, apiResponseLocalVar, files, petId);
+            if (!suppressDefaultLog)
+                Logger.LogInformation("{0,-9} | {1} | {2}", (apiResponseLocalVar.DownloadedAt - apiResponseLocalVar.RequestedAt).TotalSeconds, apiResponseLocalVar.StatusCode, apiResponseLocalVar.Path);
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="suppressDefaultLog"></param>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void AfterUploadFiles(ref bool suppressDefaultLog, IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// Logs exceptions that occur while retrieving the server response
+        /// </summary>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void OnErrorUploadFilesDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLogLocalVar = false;
+            OnErrorUploadFiles(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, files, petId);
+            if (!suppressDefaultLogLocalVar)
+                Logger.LogError(exceptionLocalVar, "An error occurred while sending the request to the server.");
+        }
+
+        /// <summary>
+        /// A partial method that gives developers a way to provide customized exception handling
+        /// </summary>
+        /// <param name="suppressDefaultLogLocalVar"></param>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void OnErrorUploadFiles(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            try
+            {
+                return await UploadFilesAsync(files, petId, cancellationToken).ConfigureAwait(false);
+            }
+            catch (Exception)
+            {
+                return null;
+            }
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            UriBuilder uriBuilderLocalVar = new UriBuilder();
+
+            try
+            {
+                ValidateUploadFiles(files);
+
+                FormatUploadFiles(files, ref petId);
+
+                using (HttpRequestMessage httpRequestMessageLocalVar = new HttpRequestMessage())
+                {
+                    uriBuilderLocalVar.Host = HttpClient.BaseAddress.Host;
+                    uriBuilderLocalVar.Port = HttpClient.BaseAddress.Port;
+                    uriBuilderLocalVar.Scheme = HttpClient.BaseAddress.Scheme;
+                    uriBuilderLocalVar.Path = HttpClient.BaseAddress.AbsolutePath == "/"
+                        ? "/pet/{petId}/uploadImages"
+                        : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImages");
+                    uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
+
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
+
+                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+
+                    List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
+
+                    foreach (Org.OpenAPITools.Client.FileParameter fileParameterLocalVar in files)
+                    {
+                        var streamContentLocalVar = new StreamContent(fileParameterLocalVar.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "files", fileParameterLocalVar.FileName ?? "files");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
+
+                    List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
+                    httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
+
+                    OAuthToken oauthTokenLocalVar1 = (OAuthToken) await OauthTokenProvider.GetAsync(cancellation: cancellationToken).ConfigureAwait(false);
+
+                    tokenBaseLocalVars.Add(oauthTokenLocalVar1);
+
+                    oauthTokenLocalVar1.UseInHeader(httpRequestMessageLocalVar, "");
+
+                    string[] contentTypes = new string[] {
+                        "multipart/form-data"
+                    };
+
+                    string[] acceptLocalVars = new string[] {
+                        "application/json"
+                    };
+
+                    IEnumerable<MediaTypeWithQualityHeaderValue> acceptHeaderValuesLocalVar = ClientUtils.SelectHeaderAcceptArray(acceptLocalVars);
+
+                    foreach (var acceptLocalVar in acceptHeaderValuesLocalVar)
+                        httpRequestMessageLocalVar.Headers.Accept.Add(acceptLocalVar);
+
+                    httpRequestMessageLocalVar.Method = HttpMethod.Post;
+
+                    DateTime requestedAtLocalVar = DateTime.UtcNow;
+
+                    using (HttpResponseMessage httpResponseMessageLocalVar = await HttpClient.SendAsync(httpRequestMessageLocalVar, cancellationToken).ConfigureAwait(false))
+                    {
+                        ILogger<UploadFilesApiResponse> apiResponseLoggerLocalVar = LoggerFactory.CreateLogger<UploadFilesApiResponse>();
+                        UploadFilesApiResponse apiResponseLocalVar;
+
+                        switch ((int)httpResponseMessageLocalVar.StatusCode) {
+                            default: {
+                                string responseContentLocalVar = await httpResponseMessageLocalVar.Content.ReadAsStringAsync(cancellationToken).ConfigureAwait(false);
+                                apiResponseLocalVar = new(apiResponseLoggerLocalVar, httpRequestMessageLocalVar, httpResponseMessageLocalVar, responseContentLocalVar, "/pet/{petId}/uploadImages", requestedAtLocalVar, _jsonSerializerOptions);
+
+                                break;
+                            }
+                        }
+
+                        AfterUploadFilesDefaultImplementation(apiResponseLocalVar, files, petId);
+
+                        Events.ExecuteOnUploadFiles(apiResponseLocalVar);
+
+                        if (apiResponseLocalVar.StatusCode == (HttpStatusCode) 429)
+                            foreach(TokenBase tokenBaseLocalVar in tokenBaseLocalVars)
+                                tokenBaseLocalVar.BeginRateLimit();
+
+                        return apiResponseLocalVar;
+                    }
+                }
+            }
+            catch(Exception e)
+            {
+                OnErrorUploadFilesDefaultImplementation(e, "/pet/{petId}/uploadImages", uriBuilderLocalVar.Path, files, petId);
+                Events.ExecuteOnErrorUploadFiles(e);
+                throw;
+            }
+        }
+
+        /// <summary>
+        /// The <see cref="UploadFilesApiResponse"/>
+        /// </summary>
+        public partial class UploadFilesApiResponse : Org.OpenAPITools.Client.ApiResponse, IUploadFilesApiResponse
+        {
+            /// <summary>
+            /// The logger
+            /// </summary>
+            public ILogger<UploadFilesApiResponse> Logger { get; }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="rawContent"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, string rawContent, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, rawContent, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="contentStream"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, System.IO.Stream contentStream, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, contentStream, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            partial void OnCreated(global::System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage);
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public bool IsOk => 200 == (int)StatusCode;
+
+            /// <summary>
+            /// Deserializes the response if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public Org.OpenAPITools.Model.ApiResponse Ok()
+            {
+                // This logic may be modified with the AsModel.mustache template
+                return IsOk
+                    ? System.Text.Json.JsonSerializer.Deserialize<Org.OpenAPITools.Model.ApiResponse>(RawContent, _jsonSerializerOptions)
+                    : null;
+            }
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok and the deserialized response is not null
+            /// </summary>
+            /// <param name="result"></param>
+            /// <returns></returns>
+            public bool TryOk([NotNullWhen(true)]out Org.OpenAPITools.Model.ApiResponse result)
+            {
+                result = null;
+
+                try
+                {
+                    result = Ok();
+                } catch (Exception e)
+                {
+                    OnDeserializationErrorDefaultImplementation(e, (HttpStatusCode)200);
+                }
+
+                return result != null;
+            }
+
+            private void OnDeserializationErrorDefaultImplementation(Exception exception, HttpStatusCode httpStatusCode)
+            {
+                bool suppressDefaultLog = false;
+                OnDeserializationError(ref suppressDefaultLog, exception, httpStatusCode);
+                if (!suppressDefaultLog)
+                    Logger.LogError(exception, "An error occurred while deserializing the {code} response.", httpStatusCode);
+            }
+
+            partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/net9/FormModels/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net9/FormModels/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..6150dbcf4774
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net9/FormModels/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,40 @@
+// <auto-generated>
+/*
+ * OpenAPI Petstore
+ *
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/.openapi-generator/FILES
index ab28c754b4b1..a3e02b328e0a 100644
--- a/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/.openapi-generator/FILES
@@ -140,6 +140,7 @@ src/Org.OpenAPITools/Client/DateOnlyNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningToken.cs
diff --git a/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/api/openapi.yaml b/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/api/openapi.yaml
index d8106a5755fc..ca451f3fb832 100644
--- a/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/api/openapi.yaml
+++ b/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/api/openapi.yaml
@@ -331,6 +331,40 @@ paths:
       summary: uploads an image
       tags:
       - pet
+  /pet/{petId}/uploadImages:
+    post:
+      description: ""
+      operationId: uploadFiles
+      parameters:
+      - description: ID of pet to update
+        explode: false
+        in: path
+        name: petId
+        required: true
+        schema:
+          format: int64
+          type: integer
+        style: simple
+      requestBody:
+        content:
+          multipart/form-data:
+            schema:
+              $ref: "#/components/schemas/uploadFiles_request"
+        required: true
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ApiResponse"
+          description: successful operation
+      security:
+      - petstore_auth:
+        - write:pets
+        - read:pets
+      summary: uploads an images
+      tags:
+      - pet
   /store/inventory:
     get:
       description: Returns a map of status codes to quantities
@@ -2924,6 +2958,16 @@ components:
           format: binary
           type: string
       type: object
+    uploadFiles_request:
+      properties:
+        files:
+          items:
+            format: binary
+            type: string
+          type: array
+      required:
+      - files
+      type: object
     testEnumParameters_request:
       properties:
         enum_form_string_array:
diff --git a/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/docs/apis/PetApi.md b/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/docs/apis/PetApi.md
index 2826ea00f728..b42ee516b313 100644
--- a/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/docs/apis/PetApi.md
+++ b/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/docs/apis/PetApi.md
@@ -13,6 +13,7 @@ All URIs are relative to *http://petstore.swagger.io:80/v2*
 | [**UpdatePetWithForm**](PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data |
 | [**UploadFile**](PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image |
 | [**UploadFileWithRequiredFile**](PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required) |
+| [**UploadFiles**](PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images |
 
 <a id="addpet"></a>
 # **AddPet**
@@ -341,3 +342,38 @@ uploads an image (required)
 
 [[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
 
+<a id="uploadfiles"></a>
+# **UploadFiles**
+> ApiResponse UploadFiles (List<System.IO.Stream> files, long petId)
+
+uploads an images
+
+
+### Parameters
+
+| Name | Type | Description | Notes |
+|------|------|-------------|-------|
+| **files** | **List&lt;System.IO.Stream&gt;** |  |  |
+| **petId** | **long** | ID of pet to update |  |
+
+### Return type
+
+[**ApiResponse**](ApiResponse.md)
+
+### Authorization
+
+[petstore_auth](../README.md#petstore_auth)
+
+### HTTP request headers
+
+ - **Content-Type**: multipart/form-data
+ - **Accept**: application/json
+
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **200** | successful operation |  -  |
+
+[[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
+
diff --git a/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs b/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
index 406dbc964a6d..d207bb93dc69 100644
--- a/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
@@ -196,7 +196,7 @@ public async Task TestEndpointParametersAsyncTest()
             string patternWithoutDelimiter = default!;
             byte[] varByte = default!;
             double varDouble = default!;
-            Client.Option<System.IO.Stream> binary = default!;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> binary = default!;
             Client.Option<string> callback = default!;
             Client.Option<DateOnly> date = default!;
             Client.Option<DateTime> dateTime = default!;
diff --git a/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/src/Org.OpenAPITools.Test/Api/PetApiTests.cs b/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
index 49e7b21b53c2..6bb1f953987c 100644
--- a/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
@@ -137,7 +137,7 @@ public async Task UploadFileAsyncTest()
         {
             long petId = default!;
             Client.Option<string> additionalMetadata = default!;
-            Client.Option<System.IO.Stream> file = default!;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> file = default!;
             var response = await _instance.UploadFileAsync(petId, additionalMetadata, file);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
@@ -150,11 +150,24 @@ public async Task UploadFileAsyncTest()
         public async Task UploadFileWithRequiredFileAsyncTest()
         {
             long petId = default!;
-            System.IO.Stream requiredFile = default!;
+            Org.OpenAPITools.Client.FileParameter requiredFile = default!;
             Client.Option<string> additionalMetadata = default!;
             var response = await _instance.UploadFileWithRequiredFileAsync(petId, requiredFile, additionalMetadata);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
         }
+
+        /// <summary>
+        /// Test UploadFiles
+        /// </summary>
+        [Fact (Skip = "not implemented")]
+        public async Task UploadFilesAsyncTest()
+        {
+            List<Org.OpenAPITools.Client.FileParameter> files = default!;
+            long petId = default!;
+            var response = await _instance.UploadFilesAsync(files, petId);
+            var model = response.Ok();
+            Assert.IsType<ApiResponse>(model);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/src/Org.OpenAPITools/Api/DefaultApi.cs b/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/src/Org.OpenAPITools/Api/DefaultApi.cs
index 2391c7e1ee03..46b798fe32ca 100644
--- a/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/src/Org.OpenAPITools/Api/DefaultApi.cs
+++ b/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/src/Org.OpenAPITools/Api/DefaultApi.cs
@@ -766,15 +766,12 @@ public async Task<IGetCountryApiResponse> GetCountryAsync(string country, System
                         ? "/country"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/country");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("country", ClientUtils.ParameterToString(country)));
 
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
-
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("country", ClientUtils.ParameterToString(country)));
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
 
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -782,11 +779,6 @@ public async Task<IGetCountryApiResponse> GetCountryAsync(string country, System
                         "application/x-www-form-urlencoded"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/src/Org.OpenAPITools/Api/FakeApi.cs b/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/src/Org.OpenAPITools/Api/FakeApi.cs
index 262a94ef2520..54a1c8c85360 100644
--- a/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/src/Org.OpenAPITools/Api/FakeApi.cs
+++ b/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/src/Org.OpenAPITools/Api/FakeApi.cs
@@ -332,7 +332,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -356,7 +356,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>?&gt;</returns>
-        Task<ITestEndpointParametersApiResponse?> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse?> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// To test enum parameters
@@ -4082,7 +4082,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<System.IO.Stream> binary, ref Option<string> callback, ref Option<DateOnly> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
+        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<Org.OpenAPITools.Client.FileParameter> binary, ref Option<string> callback, ref Option<DateOnly> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
 
         /// <summary>
         /// Validates the request parameters
@@ -4094,7 +4094,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="password"></param>
         /// <param name="varString"></param>
         /// <returns></returns>
-        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<System.IO.Stream> binary, Option<string> callback, Option<string> password, Option<string> varString)
+        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<string> password, Option<string> varString)
         {
             if (patternWithoutDelimiter == null)
                 throw new ArgumentNullException(nameof(patternWithoutDelimiter));
@@ -4133,7 +4133,7 @@ private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLog = false;
             AfterTestEndpointParameters(ref suppressDefaultLog, apiResponseLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4160,7 +4160,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -4182,7 +4182,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorTestEndpointParameters(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4211,7 +4211,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트  Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -4232,7 +4232,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse?> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse?> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -4264,7 +4264,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -4283,51 +4283,48 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         ? "/fake"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("number", ClientUtils.ParameterToString(number)));
 
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("pattern_without_delimiter", ClientUtils.ParameterToString(patternWithoutDelimiter)));
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("byte", ClientUtils.ParameterToString(varByte)));
 
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("number", ClientUtils.ParameterToString(number)));
-
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("pattern_without_delimiter", ClientUtils.ParameterToString(patternWithoutDelimiter)));
-
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("byte", ClientUtils.ParameterToString(varByte)));
-
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("double", ClientUtils.ParameterToString(varDouble)));
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("double", ClientUtils.ParameterToString(varDouble)));
 
                     if (binary.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(binary.Value));
+                        throw new NotSupportedException("File parameters cannot be sent with application/x-www-form-urlencoded. Change the operation's content type to multipart/form-data.");
 
                     if (callback.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("callback", ClientUtils.ParameterToString(callback.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("callback", ClientUtils.ParameterToString(callback.Value)));
 
                     if (date.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("date", ClientUtils.ParameterToString(date.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("date", ClientUtils.ParameterToString(date.Value)));
 
                     if (dateTime.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("dateTime", ClientUtils.ParameterToString(dateTime.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("dateTime", ClientUtils.ParameterToString(dateTime.Value)));
 
                     if (int32.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("int32", ClientUtils.ParameterToString(int32.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("int32", ClientUtils.ParameterToString(int32.Value)));
 
                     if (int64.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("int64", ClientUtils.ParameterToString(int64.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("int64", ClientUtils.ParameterToString(int64.Value)));
 
                     if (integer.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("integer", ClientUtils.ParameterToString(integer.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("integer", ClientUtils.ParameterToString(integer.Value)));
 
                     if (password.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("password", ClientUtils.ParameterToString(password.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("password", ClientUtils.ParameterToString(password.Value)));
 
                     if (varFloat.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("float", ClientUtils.ParameterToString(varFloat.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("float", ClientUtils.ParameterToString(varFloat.Value)));
 
                     if (varString.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("string", ClientUtils.ParameterToString(varString.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("string", ClientUtils.ParameterToString(varString.Value)));
+
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -4342,11 +4339,6 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         "application/x-www-form-urlencoded"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -4639,17 +4631,16 @@ public async Task<ITestEnumParametersApiResponse> TestEnumParametersAsync(Option
                     if (enumHeaderStringArray.IsSet)
                         httpRequestMessageLocalVar.Headers.Add("enum_header_string_array", ClientUtils.ParameterToString(enumHeaderStringArray.Value));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
-
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (enumFormString.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("enum_form_string", ClientUtils.ParameterToString(enumFormString.Value)));
+                    if (enumFormString.IsSet)
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("enum_form_string", ClientUtils.ParameterToString(enumFormString.Value)));
 
                     if (enumFormStringArray.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("enum_form_string_array", ClientUtils.ParameterToString(enumFormStringArray.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("enum_form_string_array", ClientUtils.ParameterToString(enumFormStringArray.Value)));
+
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
 
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -4657,11 +4648,6 @@ public async Task<ITestEnumParametersApiResponse> TestEnumParametersAsync(Option
                         "application/x-www-form-urlencoded"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Get;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -5548,17 +5534,14 @@ public async Task<ITestJsonFormDataApiResponse> TestJsonFormDataAsync(string par
                         ? "/fake/jsonFormData"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/jsonFormData");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("param", ClientUtils.ParameterToString(param)));
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("param2", ClientUtils.ParameterToString(param2)));
 
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("param", ClientUtils.ParameterToString(param)));
-
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("param2", ClientUtils.ParameterToString(param2)));
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
 
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -5566,11 +5549,6 @@ public async Task<ITestJsonFormDataApiResponse> TestJsonFormDataAsync(string par
                         "application/x-www-form-urlencoded"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Get;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/src/Org.OpenAPITools/Api/PetApi.cs b/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/src/Org.OpenAPITools/Api/PetApi.cs
index 2d7e4dab0b84..c5de9cd55ad1 100644
--- a/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/src/Org.OpenAPITools/Api/PetApi.cs
+++ b/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/src/Org.OpenAPITools/Api/PetApi.cs
@@ -218,7 +218,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image
@@ -231,7 +231,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>?&gt;</returns>
-        Task<IUploadFileApiResponse?> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse?> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -245,7 +245,7 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -258,7 +258,32 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>?&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse?> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse?> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>?&gt;</returns>
+        Task<IUploadFilesApiResponse?> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
     }
 
     /// <summary>
@@ -417,6 +442,18 @@ public interface IUploadFileWithRequiredFileApiResponse : Org.OpenAPITools.Clien
         bool IsOk { get; }
     }
 
+    /// <summary>
+    /// The <see cref="IUploadFilesApiResponse"/>
+    /// </summary>
+    public interface IUploadFilesApiResponse : Org.OpenAPITools.Client.IApiResponse, IOk<Org.OpenAPITools.Model.ApiResponse?>
+    {
+        /// <summary>
+        /// Returns true if the response is 200 Ok
+        /// </summary>
+        /// <returns></returns>
+        bool IsOk { get; }
+    }
+
     /// <summary>
     /// Represents a collection of functions to interact with the API endpoints
     /// </summary>
@@ -601,6 +638,26 @@ internal void ExecuteOnErrorUploadFileWithRequiredFile(Exception exception)
         {
             OnErrorUploadFileWithRequiredFile?.Invoke(this, new ExceptionEventArgs(exception));
         }
+
+        /// <summary>
+        /// The event raised after the server response
+        /// </summary>
+        public event EventHandler<ApiResponseEventArgs>? OnUploadFiles;
+
+        /// <summary>
+        /// The event raised after an error querying the server
+        /// </summary>
+        public event EventHandler<ExceptionEventArgs>? OnErrorUploadFiles;
+
+        internal void ExecuteOnUploadFiles(PetApi.UploadFilesApiResponse apiResponse)
+        {
+            OnUploadFiles?.Invoke(this, new ApiResponseEventArgs(apiResponse));
+        }
+
+        internal void ExecuteOnErrorUploadFiles(Exception exception)
+        {
+            OnErrorUploadFiles?.Invoke(this, new ExceptionEventArgs(exception));
+        }
     }
 
     /// <summary>
@@ -2332,17 +2389,16 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (name.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("name", ClientUtils.ParameterToString(name.Value)));
+                    if (name.IsSet)
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("name", ClientUtils.ParameterToString(name.Value)));
 
                     if (status.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("status", ClientUtils.ParameterToString(status.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("status", ClientUtils.ParameterToString(status.Value)));
+
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -2357,11 +2413,6 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         "application/x-www-form-urlencoded"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -2461,7 +2512,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<System.IO.Stream> file);
+        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Validates the request parameters
@@ -2469,7 +2520,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
         /// <returns></returns>
-        private void ValidateUploadFile(Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void ValidateUploadFile(Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             if (additionalMetadata.IsSet && additionalMetadata.Value == null)
                 throw new ArgumentNullException(nameof(additionalMetadata));
@@ -2485,7 +2536,7 @@ private void ValidateUploadFile(Option<string> additionalMetadata, Option<System
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLog = false;
             AfterUploadFile(ref suppressDefaultLog, apiResponseLocalVar, petId, additionalMetadata, file);
@@ -2501,7 +2552,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2512,7 +2563,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, additionalMetadata, file);
@@ -2530,7 +2581,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// uploads an image 
@@ -2540,7 +2591,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse?> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse?> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2561,7 +2612,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2581,17 +2632,23 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImage");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (additionalMetadata.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
+                    if (additionalMetadata.IsSet)
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
 
                     if (file.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(file.Value));
+                    {
+                        var streamContentLocalVar = new StreamContent(file.Value.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "file", file.Value.FileName ?? "file");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -2606,11 +2663,6 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         "multipart/form-data"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json"
                     };
@@ -2751,7 +2803,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFileWithRequiredFile(ref long petId, ref System.IO.Stream requiredFile, ref Option<string> additionalMetadata);
+        partial void FormatUploadFileWithRequiredFile(ref long petId, ref Org.OpenAPITools.Client.FileParameter requiredFile, ref Option<string> additionalMetadata);
 
         /// <summary>
         /// Validates the request parameters
@@ -2759,7 +2811,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
         /// <returns></returns>
-        private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void ValidateUploadFileWithRequiredFile(Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             if (requiredFile == null)
                 throw new ArgumentNullException(nameof(requiredFile));
@@ -2775,7 +2827,7 @@ private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, O
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLog = false;
             AfterUploadFileWithRequiredFile(ref suppressDefaultLog, apiResponseLocalVar, petId, requiredFile, additionalMetadata);
@@ -2791,7 +2843,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2802,7 +2854,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFileWithRequiredFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, requiredFile, additionalMetadata);
@@ -2820,7 +2872,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// uploads an image (required) 
@@ -2830,7 +2882,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse?> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse?> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2851,7 +2903,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2871,16 +2923,22 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/{petId}/uploadImageWithRequiredFile");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    multipartContentLocalVar.Add(new StreamContent(requiredFile));
+                    {
+                        var streamContentLocalVar = new StreamContent(requiredFile.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "requiredFile", requiredFile.FileName ?? "requiredFile");
+                    }
 
                     if (additionalMetadata.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -2895,11 +2953,6 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         "multipart/form-data"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json",
                         "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
@@ -3040,5 +3093,283 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
 
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
+
+        partial void FormatUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files, ref long petId);
+
+        /// <summary>
+        /// Validates the request parameters
+        /// </summary>
+        /// <param name="files"></param>
+        /// <returns></returns>
+        private void ValidateUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files)
+        {
+            if (files == null)
+                throw new ArgumentNullException(nameof(files));
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void AfterUploadFilesDefaultImplementation(IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLog = false;
+            AfterUploadFiles(ref suppressDefaultLog, apiResponseLocalVar, files, petId);
+            if (!suppressDefaultLog)
+                Logger.LogInformation("{0,-9} | {1} | {2}", (apiResponseLocalVar.DownloadedAt - apiResponseLocalVar.RequestedAt).TotalSeconds, apiResponseLocalVar.StatusCode, apiResponseLocalVar.Path);
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="suppressDefaultLog"></param>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void AfterUploadFiles(ref bool suppressDefaultLog, IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// Logs exceptions that occur while retrieving the server response
+        /// </summary>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void OnErrorUploadFilesDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLogLocalVar = false;
+            OnErrorUploadFiles(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, files, petId);
+            if (!suppressDefaultLogLocalVar)
+                Logger.LogError(exceptionLocalVar, "An error occurred while sending the request to the server.");
+        }
+
+        /// <summary>
+        /// A partial method that gives developers a way to provide customized exception handling
+        /// </summary>
+        /// <param name="suppressDefaultLogLocalVar"></param>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void OnErrorUploadFiles(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse?> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            try
+            {
+                return await UploadFilesAsync(files, petId, cancellationToken).ConfigureAwait(false);
+            }
+            catch (Exception)
+            {
+                return null;
+            }
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            UriBuilder uriBuilderLocalVar = new UriBuilder();
+
+            try
+            {
+                ValidateUploadFiles(files);
+
+                FormatUploadFiles(files, ref petId);
+
+                using (HttpRequestMessage httpRequestMessageLocalVar = new HttpRequestMessage())
+                {
+                    uriBuilderLocalVar.Host = HttpClient.BaseAddress!.Host;
+                    uriBuilderLocalVar.Port = HttpClient.BaseAddress.Port;
+                    uriBuilderLocalVar.Scheme = HttpClient.BaseAddress.Scheme;
+                    uriBuilderLocalVar.Path = HttpClient.BaseAddress.AbsolutePath == "/"
+                        ? "/pet/{petId}/uploadImages"
+                        : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImages");
+                    uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
+
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
+
+                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
+
+                    foreach (Org.OpenAPITools.Client.FileParameter fileParameterLocalVar in files)
+                    {
+                        var streamContentLocalVar = new StreamContent(fileParameterLocalVar.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "files", fileParameterLocalVar.FileName ?? "files");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
+
+                    List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
+                    httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
+
+                    OAuthToken oauthTokenLocalVar1 = (OAuthToken) await OauthTokenProvider.GetAsync(cancellation: cancellationToken).ConfigureAwait(false);
+
+                    tokenBaseLocalVars.Add(oauthTokenLocalVar1);
+
+                    oauthTokenLocalVar1.UseInHeader(httpRequestMessageLocalVar, "");
+
+                    string[] contentTypes = new string[] {
+                        "multipart/form-data"
+                    };
+
+                    string[] acceptLocalVars = new string[] {
+                        "application/json"
+                    };
+
+                    IEnumerable<MediaTypeWithQualityHeaderValue> acceptHeaderValuesLocalVar = ClientUtils.SelectHeaderAcceptArray(acceptLocalVars);
+
+                    foreach (var acceptLocalVar in acceptHeaderValuesLocalVar)
+                        httpRequestMessageLocalVar.Headers.Accept.Add(acceptLocalVar);
+
+                    httpRequestMessageLocalVar.Method = HttpMethod.Post;
+
+                    DateTime requestedAtLocalVar = DateTime.UtcNow;
+
+                    using (HttpResponseMessage httpResponseMessageLocalVar = await HttpClient.SendAsync(httpRequestMessageLocalVar, cancellationToken).ConfigureAwait(false))
+                    {
+                        ILogger<UploadFilesApiResponse> apiResponseLoggerLocalVar = LoggerFactory.CreateLogger<UploadFilesApiResponse>();
+                        UploadFilesApiResponse apiResponseLocalVar;
+
+                        switch ((int)httpResponseMessageLocalVar.StatusCode) {
+                            default: {
+                                string responseContentLocalVar = await httpResponseMessageLocalVar.Content.ReadAsStringAsync(cancellationToken).ConfigureAwait(false);
+                                apiResponseLocalVar = new(apiResponseLoggerLocalVar, httpRequestMessageLocalVar, httpResponseMessageLocalVar, responseContentLocalVar, "/pet/{petId}/uploadImages", requestedAtLocalVar, _jsonSerializerOptions);
+
+                                break;
+                            }
+                        }
+
+                        AfterUploadFilesDefaultImplementation(apiResponseLocalVar, files, petId);
+
+                        Events.ExecuteOnUploadFiles(apiResponseLocalVar);
+
+                        if (apiResponseLocalVar.StatusCode == (HttpStatusCode) 429)
+                            foreach(TokenBase tokenBaseLocalVar in tokenBaseLocalVars)
+                                tokenBaseLocalVar.BeginRateLimit();
+
+                        return apiResponseLocalVar;
+                    }
+                }
+            }
+            catch(Exception e)
+            {
+                OnErrorUploadFilesDefaultImplementation(e, "/pet/{petId}/uploadImages", uriBuilderLocalVar.Path, files, petId);
+                Events.ExecuteOnErrorUploadFiles(e);
+                throw;
+            }
+        }
+
+        /// <summary>
+        /// The <see cref="UploadFilesApiResponse"/>
+        /// </summary>
+        public partial class UploadFilesApiResponse : Org.OpenAPITools.Client.ApiResponse, IUploadFilesApiResponse
+        {
+            /// <summary>
+            /// The logger
+            /// </summary>
+            public ILogger<UploadFilesApiResponse> Logger { get; }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="rawContent"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, string rawContent, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, rawContent, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="contentStream"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, System.IO.Stream contentStream, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, contentStream, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            partial void OnCreated(global::System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage);
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public bool IsOk => 200 == (int)StatusCode;
+
+            /// <summary>
+            /// Deserializes the response if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public Org.OpenAPITools.Model.ApiResponse? Ok()
+            {
+                // This logic may be modified with the AsModel.mustache template
+                return IsOk
+                    ? System.Text.Json.JsonSerializer.Deserialize<Org.OpenAPITools.Model.ApiResponse>(RawContent, _jsonSerializerOptions)
+                    : null;
+            }
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok and the deserialized response is not null
+            /// </summary>
+            /// <param name="result"></param>
+            /// <returns></returns>
+            public bool TryOk([NotNullWhen(true)]out Org.OpenAPITools.Model.ApiResponse? result)
+            {
+                result = null;
+
+                try
+                {
+                    result = Ok();
+                } catch (Exception e)
+                {
+                    OnDeserializationErrorDefaultImplementation(e, (HttpStatusCode)200);
+                }
+
+                return result != null;
+            }
+
+            private void OnDeserializationErrorDefaultImplementation(Exception exception, HttpStatusCode httpStatusCode)
+            {
+                bool suppressDefaultLog = false;
+                OnDeserializationError(ref suppressDefaultLog, exception, httpStatusCode);
+                if (!suppressDefaultLog)
+                    Logger.LogError(exception, "An error occurred while deserializing the {code} response.", httpStatusCode);
+            }
+
+            partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..77779fe7d75a
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net9/NullReferenceTypes/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,42 @@
+// <auto-generated>
+/*
+ * OpenAPI Petstore
+ *
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+#nullable enable
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string? FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string? fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net9/OneOf/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net9/OneOf/.openapi-generator/FILES
index a36efde4422e..cfb76c7ed0ac 100644
--- a/samples/client/petstore/csharp/generichost/net9/OneOf/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net9/OneOf/.openapi-generator/FILES
@@ -26,6 +26,7 @@ src/Org.OpenAPITools/Client/DateOnlyNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/JsonSerializerOptionsProvider.cs
 src/Org.OpenAPITools/Client/Option.cs
diff --git a/samples/client/petstore/csharp/generichost/net9/OneOf/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net9/OneOf/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..e629f4afdaec
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net9/OneOf/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,42 @@
+// <auto-generated>
+/*
+ * fruity
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * The version of the OpenAPI document: 0.0.1
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+#nullable enable
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string? FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string? fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net9/Petstore/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net9/Petstore/.openapi-generator/FILES
index ab28c754b4b1..a3e02b328e0a 100644
--- a/samples/client/petstore/csharp/generichost/net9/Petstore/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net9/Petstore/.openapi-generator/FILES
@@ -140,6 +140,7 @@ src/Org.OpenAPITools/Client/DateOnlyNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningToken.cs
diff --git a/samples/client/petstore/csharp/generichost/net9/Petstore/api/openapi.yaml b/samples/client/petstore/csharp/generichost/net9/Petstore/api/openapi.yaml
index d8106a5755fc..ca451f3fb832 100644
--- a/samples/client/petstore/csharp/generichost/net9/Petstore/api/openapi.yaml
+++ b/samples/client/petstore/csharp/generichost/net9/Petstore/api/openapi.yaml
@@ -331,6 +331,40 @@ paths:
       summary: uploads an image
       tags:
       - pet
+  /pet/{petId}/uploadImages:
+    post:
+      description: ""
+      operationId: uploadFiles
+      parameters:
+      - description: ID of pet to update
+        explode: false
+        in: path
+        name: petId
+        required: true
+        schema:
+          format: int64
+          type: integer
+        style: simple
+      requestBody:
+        content:
+          multipart/form-data:
+            schema:
+              $ref: "#/components/schemas/uploadFiles_request"
+        required: true
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ApiResponse"
+          description: successful operation
+      security:
+      - petstore_auth:
+        - write:pets
+        - read:pets
+      summary: uploads an images
+      tags:
+      - pet
   /store/inventory:
     get:
       description: Returns a map of status codes to quantities
@@ -2924,6 +2958,16 @@ components:
           format: binary
           type: string
       type: object
+    uploadFiles_request:
+      properties:
+        files:
+          items:
+            format: binary
+            type: string
+          type: array
+      required:
+      - files
+      type: object
     testEnumParameters_request:
       properties:
         enum_form_string_array:
diff --git a/samples/client/petstore/csharp/generichost/net9/Petstore/docs/apis/PetApi.md b/samples/client/petstore/csharp/generichost/net9/Petstore/docs/apis/PetApi.md
index 2826ea00f728..b42ee516b313 100644
--- a/samples/client/petstore/csharp/generichost/net9/Petstore/docs/apis/PetApi.md
+++ b/samples/client/petstore/csharp/generichost/net9/Petstore/docs/apis/PetApi.md
@@ -13,6 +13,7 @@ All URIs are relative to *http://petstore.swagger.io:80/v2*
 | [**UpdatePetWithForm**](PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data |
 | [**UploadFile**](PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image |
 | [**UploadFileWithRequiredFile**](PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required) |
+| [**UploadFiles**](PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images |
 
 <a id="addpet"></a>
 # **AddPet**
@@ -341,3 +342,38 @@ uploads an image (required)
 
 [[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
 
+<a id="uploadfiles"></a>
+# **UploadFiles**
+> ApiResponse UploadFiles (List<System.IO.Stream> files, long petId)
+
+uploads an images
+
+
+### Parameters
+
+| Name | Type | Description | Notes |
+|------|------|-------------|-------|
+| **files** | **List&lt;System.IO.Stream&gt;** |  |  |
+| **petId** | **long** | ID of pet to update |  |
+
+### Return type
+
+[**ApiResponse**](ApiResponse.md)
+
+### Authorization
+
+[petstore_auth](../README.md#petstore_auth)
+
+### HTTP request headers
+
+ - **Content-Type**: multipart/form-data
+ - **Accept**: application/json
+
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **200** | successful operation |  -  |
+
+[[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
+
diff --git a/samples/client/petstore/csharp/generichost/net9/Petstore/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs b/samples/client/petstore/csharp/generichost/net9/Petstore/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
index 66769b3aee6a..fed093fb206f 100644
--- a/samples/client/petstore/csharp/generichost/net9/Petstore/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/net9/Petstore/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
@@ -196,7 +196,7 @@ public async Task TestEndpointParametersAsyncTest()
             string patternWithoutDelimiter = default;
             byte[] varByte = default;
             double varDouble = default;
-            Client.Option<System.IO.Stream> binary = default;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> binary = default;
             Client.Option<string> callback = default;
             Client.Option<DateOnly> date = default;
             Client.Option<DateTime> dateTime = default;
diff --git a/samples/client/petstore/csharp/generichost/net9/Petstore/src/Org.OpenAPITools.Test/Api/PetApiTests.cs b/samples/client/petstore/csharp/generichost/net9/Petstore/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
index 215e88093797..e9b05337bb59 100644
--- a/samples/client/petstore/csharp/generichost/net9/Petstore/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/net9/Petstore/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
@@ -137,7 +137,7 @@ public async Task UploadFileAsyncTest()
         {
             long petId = default;
             Client.Option<string> additionalMetadata = default;
-            Client.Option<System.IO.Stream> file = default;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> file = default;
             var response = await _instance.UploadFileAsync(petId, additionalMetadata, file);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
@@ -150,11 +150,24 @@ public async Task UploadFileAsyncTest()
         public async Task UploadFileWithRequiredFileAsyncTest()
         {
             long petId = default;
-            System.IO.Stream requiredFile = default;
+            Org.OpenAPITools.Client.FileParameter requiredFile = default;
             Client.Option<string> additionalMetadata = default;
             var response = await _instance.UploadFileWithRequiredFileAsync(petId, requiredFile, additionalMetadata);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
         }
+
+        /// <summary>
+        /// Test UploadFiles
+        /// </summary>
+        [Fact (Skip = "not implemented")]
+        public async Task UploadFilesAsyncTest()
+        {
+            List<Org.OpenAPITools.Client.FileParameter> files = default;
+            long petId = default;
+            var response = await _instance.UploadFilesAsync(files, petId);
+            var model = response.Ok();
+            Assert.IsType<ApiResponse>(model);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/net9/Petstore/src/Org.OpenAPITools/Api/DefaultApi.cs b/samples/client/petstore/csharp/generichost/net9/Petstore/src/Org.OpenAPITools/Api/DefaultApi.cs
index 3c26a27185e6..44d52e7e1090 100644
--- a/samples/client/petstore/csharp/generichost/net9/Petstore/src/Org.OpenAPITools/Api/DefaultApi.cs
+++ b/samples/client/petstore/csharp/generichost/net9/Petstore/src/Org.OpenAPITools/Api/DefaultApi.cs
@@ -764,27 +764,19 @@ public async Task<IGetCountryApiResponse> GetCountryAsync(string country, System
                         ? "/country"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/country");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("country", ClientUtils.ParameterToString(country)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/net9/Petstore/src/Org.OpenAPITools/Api/FakeApi.cs b/samples/client/petstore/csharp/generichost/net9/Petstore/src/Org.OpenAPITools/Api/FakeApi.cs
index 01aaf0ccbd85..482421f8c4ea 100644
--- a/samples/client/petstore/csharp/generichost/net9/Petstore/src/Org.OpenAPITools/Api/FakeApi.cs
+++ b/samples/client/petstore/csharp/generichost/net9/Petstore/src/Org.OpenAPITools/Api/FakeApi.cs
@@ -330,7 +330,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -354,7 +354,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// To test enum parameters
@@ -4080,7 +4080,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<System.IO.Stream> binary, ref Option<string> callback, ref Option<DateOnly> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
+        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<Org.OpenAPITools.Client.FileParameter> binary, ref Option<string> callback, ref Option<DateOnly> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
 
         /// <summary>
         /// Validates the request parameters
@@ -4092,7 +4092,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="password"></param>
         /// <param name="varString"></param>
         /// <returns></returns>
-        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<System.IO.Stream> binary, Option<string> callback, Option<string> password, Option<string> varString)
+        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<string> password, Option<string> varString)
         {
             if (patternWithoutDelimiter == null)
                 throw new ArgumentNullException(nameof(patternWithoutDelimiter));
@@ -4131,7 +4131,7 @@ private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLog = false;
             AfterTestEndpointParameters(ref suppressDefaultLog, apiResponseLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4158,7 +4158,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -4180,7 +4180,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorTestEndpointParameters(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4209,7 +4209,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트  Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -4230,7 +4230,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -4262,7 +4262,7 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDe
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -4281,14 +4281,8 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         ? "/fake"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("number", ClientUtils.ParameterToString(number)));
 
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("pattern_without_delimiter", ClientUtils.ParameterToString(patternWithoutDelimiter)));
@@ -4298,7 +4292,7 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("double", ClientUtils.ParameterToString(varDouble)));
 
                     if (binary.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(binary.Value));
+                        throw new NotSupportedException("File parameters cannot be sent with application/x-www-form-urlencoded. Change the operation's content type to multipart/form-data.");
 
                     if (callback.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("callback", ClientUtils.ParameterToString(callback.Value)));
@@ -4327,6 +4321,9 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                     if (varString.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("string", ClientUtils.ParameterToString(varString.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -4340,11 +4337,6 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -4637,29 +4629,23 @@ public async Task<ITestEnumParametersApiResponse> TestEnumParametersAsync(Option
                     if (enumHeaderStringArray.IsSet)
                         httpRequestMessageLocalVar.Headers.Add("enum_header_string_array", ClientUtils.ParameterToString(enumHeaderStringArray.Value));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (enumFormString.IsSet)
+                    if (enumFormString.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("enum_form_string", ClientUtils.ParameterToString(enumFormString.Value)));
 
                     if (enumFormStringArray.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("enum_form_string_array", ClientUtils.ParameterToString(enumFormStringArray.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Get;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -5546,29 +5532,21 @@ public async Task<ITestJsonFormDataApiResponse> TestJsonFormDataAsync(string par
                         ? "/fake/jsonFormData"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/jsonFormData");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("param", ClientUtils.ParameterToString(param)));
 
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("param2", ClientUtils.ParameterToString(param2)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Get;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/net9/Petstore/src/Org.OpenAPITools/Api/PetApi.cs b/samples/client/petstore/csharp/generichost/net9/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
index a1817e3df697..da4dfd225bc4 100644
--- a/samples/client/petstore/csharp/generichost/net9/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
+++ b/samples/client/petstore/csharp/generichost/net9/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
@@ -216,7 +216,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image
@@ -229,7 +229,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -243,7 +243,7 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -256,7 +256,32 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        Task<IUploadFilesApiResponse> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
     }
 
     /// <summary>
@@ -415,6 +440,18 @@ public interface IUploadFileWithRequiredFileApiResponse : Org.OpenAPITools.Clien
         bool IsOk { get; }
     }
 
+    /// <summary>
+    /// The <see cref="IUploadFilesApiResponse"/>
+    /// </summary>
+    public interface IUploadFilesApiResponse : Org.OpenAPITools.Client.IApiResponse, IOk<Org.OpenAPITools.Model.ApiResponse>
+    {
+        /// <summary>
+        /// Returns true if the response is 200 Ok
+        /// </summary>
+        /// <returns></returns>
+        bool IsOk { get; }
+    }
+
     /// <summary>
     /// Represents a collection of functions to interact with the API endpoints
     /// </summary>
@@ -599,6 +636,26 @@ internal void ExecuteOnErrorUploadFileWithRequiredFile(Exception exception)
         {
             OnErrorUploadFileWithRequiredFile?.Invoke(this, new ExceptionEventArgs(exception));
         }
+
+        /// <summary>
+        /// The event raised after the server response
+        /// </summary>
+        public event EventHandler<ApiResponseEventArgs> OnUploadFiles;
+
+        /// <summary>
+        /// The event raised after an error querying the server
+        /// </summary>
+        public event EventHandler<ExceptionEventArgs> OnErrorUploadFiles;
+
+        internal void ExecuteOnUploadFiles(PetApi.UploadFilesApiResponse apiResponse)
+        {
+            OnUploadFiles?.Invoke(this, new ApiResponseEventArgs(apiResponse));
+        }
+
+        internal void ExecuteOnErrorUploadFiles(Exception exception)
+        {
+            OnErrorUploadFiles?.Invoke(this, new ExceptionEventArgs(exception));
+        }
     }
 
     /// <summary>
@@ -2330,18 +2387,17 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (name.IsSet)
+                    if (name.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("name", ClientUtils.ParameterToString(name.Value)));
 
                     if (status.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("status", ClientUtils.ParameterToString(status.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -2355,11 +2411,6 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -2459,7 +2510,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<System.IO.Stream> file);
+        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Validates the request parameters
@@ -2467,7 +2518,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
         /// <returns></returns>
-        private void ValidateUploadFile(Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void ValidateUploadFile(Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             if (additionalMetadata.IsSet && additionalMetadata.Value == null)
                 throw new ArgumentNullException(nameof(additionalMetadata));
@@ -2483,7 +2534,7 @@ private void ValidateUploadFile(Option<string> additionalMetadata, Option<System
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLog = false;
             AfterUploadFile(ref suppressDefaultLog, apiResponseLocalVar, petId, additionalMetadata, file);
@@ -2499,7 +2550,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2510,7 +2561,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, additionalMetadata, file);
@@ -2528,7 +2579,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// uploads an image 
@@ -2538,7 +2589,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2559,7 +2610,7 @@ public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, O
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2579,17 +2630,23 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImage");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (additionalMetadata.IsSet)
+                    if (additionalMetadata.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
 
                     if (file.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(file.Value));
+                    {
+                        var streamContentLocalVar = new StreamContent(file.Value.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "file", file.Value.FileName ?? "file");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -2604,11 +2661,6 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         "multipart/form-data"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json"
                     };
@@ -2749,7 +2801,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFileWithRequiredFile(ref long petId, ref System.IO.Stream requiredFile, ref Option<string> additionalMetadata);
+        partial void FormatUploadFileWithRequiredFile(ref long petId, ref Org.OpenAPITools.Client.FileParameter requiredFile, ref Option<string> additionalMetadata);
 
         /// <summary>
         /// Validates the request parameters
@@ -2757,7 +2809,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
         /// <returns></returns>
-        private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void ValidateUploadFileWithRequiredFile(Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             if (requiredFile == null)
                 throw new ArgumentNullException(nameof(requiredFile));
@@ -2773,7 +2825,7 @@ private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, O
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLog = false;
             AfterUploadFileWithRequiredFile(ref suppressDefaultLog, apiResponseLocalVar, petId, requiredFile, additionalMetadata);
@@ -2789,7 +2841,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2800,7 +2852,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFileWithRequiredFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, requiredFile, additionalMetadata);
@@ -2818,7 +2870,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// uploads an image (required) 
@@ -2828,7 +2880,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2849,7 +2901,7 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2869,17 +2921,23 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/{petId}/uploadImageWithRequiredFile");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    multipartContentLocalVar.Add(new StreamContent(requiredFile));
+                    {
+                        var streamContentLocalVar = new StreamContent(requiredFile.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "requiredFile", requiredFile.FileName ?? "requiredFile");
+                    }
 
                     if (additionalMetadata.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
 
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -2893,11 +2951,6 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         "multipart/form-data"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json",
                         "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
@@ -3038,5 +3091,283 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
 
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
+
+        partial void FormatUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files, ref long petId);
+
+        /// <summary>
+        /// Validates the request parameters
+        /// </summary>
+        /// <param name="files"></param>
+        /// <returns></returns>
+        private void ValidateUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files)
+        {
+            if (files == null)
+                throw new ArgumentNullException(nameof(files));
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void AfterUploadFilesDefaultImplementation(IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLog = false;
+            AfterUploadFiles(ref suppressDefaultLog, apiResponseLocalVar, files, petId);
+            if (!suppressDefaultLog)
+                Logger.LogInformation("{0,-9} | {1} | {2}", (apiResponseLocalVar.DownloadedAt - apiResponseLocalVar.RequestedAt).TotalSeconds, apiResponseLocalVar.StatusCode, apiResponseLocalVar.Path);
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="suppressDefaultLog"></param>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void AfterUploadFiles(ref bool suppressDefaultLog, IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// Logs exceptions that occur while retrieving the server response
+        /// </summary>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void OnErrorUploadFilesDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLogLocalVar = false;
+            OnErrorUploadFiles(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, files, petId);
+            if (!suppressDefaultLogLocalVar)
+                Logger.LogError(exceptionLocalVar, "An error occurred while sending the request to the server.");
+        }
+
+        /// <summary>
+        /// A partial method that gives developers a way to provide customized exception handling
+        /// </summary>
+        /// <param name="suppressDefaultLogLocalVar"></param>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void OnErrorUploadFiles(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            try
+            {
+                return await UploadFilesAsync(files, petId, cancellationToken).ConfigureAwait(false);
+            }
+            catch (Exception)
+            {
+                return null;
+            }
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            UriBuilder uriBuilderLocalVar = new UriBuilder();
+
+            try
+            {
+                ValidateUploadFiles(files);
+
+                FormatUploadFiles(files, ref petId);
+
+                using (HttpRequestMessage httpRequestMessageLocalVar = new HttpRequestMessage())
+                {
+                    uriBuilderLocalVar.Host = HttpClient.BaseAddress.Host;
+                    uriBuilderLocalVar.Port = HttpClient.BaseAddress.Port;
+                    uriBuilderLocalVar.Scheme = HttpClient.BaseAddress.Scheme;
+                    uriBuilderLocalVar.Path = HttpClient.BaseAddress.AbsolutePath == "/"
+                        ? "/pet/{petId}/uploadImages"
+                        : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImages");
+                    uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
+
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
+
+                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+
+                    List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
+
+                    foreach (Org.OpenAPITools.Client.FileParameter fileParameterLocalVar in files)
+                    {
+                        var streamContentLocalVar = new StreamContent(fileParameterLocalVar.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "files", fileParameterLocalVar.FileName ?? "files");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
+
+                    List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
+                    httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
+
+                    OAuthToken oauthTokenLocalVar1 = (OAuthToken) await OauthTokenProvider.GetAsync(cancellation: cancellationToken).ConfigureAwait(false);
+
+                    tokenBaseLocalVars.Add(oauthTokenLocalVar1);
+
+                    oauthTokenLocalVar1.UseInHeader(httpRequestMessageLocalVar, "");
+
+                    string[] contentTypes = new string[] {
+                        "multipart/form-data"
+                    };
+
+                    string[] acceptLocalVars = new string[] {
+                        "application/json"
+                    };
+
+                    IEnumerable<MediaTypeWithQualityHeaderValue> acceptHeaderValuesLocalVar = ClientUtils.SelectHeaderAcceptArray(acceptLocalVars);
+
+                    foreach (var acceptLocalVar in acceptHeaderValuesLocalVar)
+                        httpRequestMessageLocalVar.Headers.Accept.Add(acceptLocalVar);
+
+                    httpRequestMessageLocalVar.Method = HttpMethod.Post;
+
+                    DateTime requestedAtLocalVar = DateTime.UtcNow;
+
+                    using (HttpResponseMessage httpResponseMessageLocalVar = await HttpClient.SendAsync(httpRequestMessageLocalVar, cancellationToken).ConfigureAwait(false))
+                    {
+                        ILogger<UploadFilesApiResponse> apiResponseLoggerLocalVar = LoggerFactory.CreateLogger<UploadFilesApiResponse>();
+                        UploadFilesApiResponse apiResponseLocalVar;
+
+                        switch ((int)httpResponseMessageLocalVar.StatusCode) {
+                            default: {
+                                string responseContentLocalVar = await httpResponseMessageLocalVar.Content.ReadAsStringAsync(cancellationToken).ConfigureAwait(false);
+                                apiResponseLocalVar = new(apiResponseLoggerLocalVar, httpRequestMessageLocalVar, httpResponseMessageLocalVar, responseContentLocalVar, "/pet/{petId}/uploadImages", requestedAtLocalVar, _jsonSerializerOptions);
+
+                                break;
+                            }
+                        }
+
+                        AfterUploadFilesDefaultImplementation(apiResponseLocalVar, files, petId);
+
+                        Events.ExecuteOnUploadFiles(apiResponseLocalVar);
+
+                        if (apiResponseLocalVar.StatusCode == (HttpStatusCode) 429)
+                            foreach(TokenBase tokenBaseLocalVar in tokenBaseLocalVars)
+                                tokenBaseLocalVar.BeginRateLimit();
+
+                        return apiResponseLocalVar;
+                    }
+                }
+            }
+            catch(Exception e)
+            {
+                OnErrorUploadFilesDefaultImplementation(e, "/pet/{petId}/uploadImages", uriBuilderLocalVar.Path, files, petId);
+                Events.ExecuteOnErrorUploadFiles(e);
+                throw;
+            }
+        }
+
+        /// <summary>
+        /// The <see cref="UploadFilesApiResponse"/>
+        /// </summary>
+        public partial class UploadFilesApiResponse : Org.OpenAPITools.Client.ApiResponse, IUploadFilesApiResponse
+        {
+            /// <summary>
+            /// The logger
+            /// </summary>
+            public ILogger<UploadFilesApiResponse> Logger { get; }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="rawContent"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, string rawContent, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, rawContent, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="contentStream"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, System.IO.Stream contentStream, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, contentStream, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            partial void OnCreated(global::System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage);
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public bool IsOk => 200 == (int)StatusCode;
+
+            /// <summary>
+            /// Deserializes the response if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public Org.OpenAPITools.Model.ApiResponse Ok()
+            {
+                // This logic may be modified with the AsModel.mustache template
+                return IsOk
+                    ? System.Text.Json.JsonSerializer.Deserialize<Org.OpenAPITools.Model.ApiResponse>(RawContent, _jsonSerializerOptions)
+                    : null;
+            }
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok and the deserialized response is not null
+            /// </summary>
+            /// <param name="result"></param>
+            /// <returns></returns>
+            public bool TryOk([NotNullWhen(true)]out Org.OpenAPITools.Model.ApiResponse result)
+            {
+                result = null;
+
+                try
+                {
+                    result = Ok();
+                } catch (Exception e)
+                {
+                    OnDeserializationErrorDefaultImplementation(e, (HttpStatusCode)200);
+                }
+
+                return result != null;
+            }
+
+            private void OnDeserializationErrorDefaultImplementation(Exception exception, HttpStatusCode httpStatusCode)
+            {
+                bool suppressDefaultLog = false;
+                OnDeserializationError(ref suppressDefaultLog, exception, httpStatusCode);
+                if (!suppressDefaultLog)
+                    Logger.LogError(exception, "An error occurred while deserializing the {code} response.", httpStatusCode);
+            }
+
+            partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/net9/Petstore/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net9/Petstore/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..6150dbcf4774
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net9/Petstore/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,40 @@
+// <auto-generated>
+/*
+ * OpenAPI Petstore
+ *
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net9/SourceGeneration/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net9/SourceGeneration/.openapi-generator/FILES
index ab28c754b4b1..a3e02b328e0a 100644
--- a/samples/client/petstore/csharp/generichost/net9/SourceGeneration/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net9/SourceGeneration/.openapi-generator/FILES
@@ -140,6 +140,7 @@ src/Org.OpenAPITools/Client/DateOnlyNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningToken.cs
diff --git a/samples/client/petstore/csharp/generichost/net9/SourceGeneration/api/openapi.yaml b/samples/client/petstore/csharp/generichost/net9/SourceGeneration/api/openapi.yaml
index d8106a5755fc..ca451f3fb832 100644
--- a/samples/client/petstore/csharp/generichost/net9/SourceGeneration/api/openapi.yaml
+++ b/samples/client/petstore/csharp/generichost/net9/SourceGeneration/api/openapi.yaml
@@ -331,6 +331,40 @@ paths:
       summary: uploads an image
       tags:
       - pet
+  /pet/{petId}/uploadImages:
+    post:
+      description: ""
+      operationId: uploadFiles
+      parameters:
+      - description: ID of pet to update
+        explode: false
+        in: path
+        name: petId
+        required: true
+        schema:
+          format: int64
+          type: integer
+        style: simple
+      requestBody:
+        content:
+          multipart/form-data:
+            schema:
+              $ref: "#/components/schemas/uploadFiles_request"
+        required: true
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ApiResponse"
+          description: successful operation
+      security:
+      - petstore_auth:
+        - write:pets
+        - read:pets
+      summary: uploads an images
+      tags:
+      - pet
   /store/inventory:
     get:
       description: Returns a map of status codes to quantities
@@ -2924,6 +2958,16 @@ components:
           format: binary
           type: string
       type: object
+    uploadFiles_request:
+      properties:
+        files:
+          items:
+            format: binary
+            type: string
+          type: array
+      required:
+      - files
+      type: object
     testEnumParameters_request:
       properties:
         enum_form_string_array:
diff --git a/samples/client/petstore/csharp/generichost/net9/SourceGeneration/docs/apis/PetApi.md b/samples/client/petstore/csharp/generichost/net9/SourceGeneration/docs/apis/PetApi.md
index 2826ea00f728..b42ee516b313 100644
--- a/samples/client/petstore/csharp/generichost/net9/SourceGeneration/docs/apis/PetApi.md
+++ b/samples/client/petstore/csharp/generichost/net9/SourceGeneration/docs/apis/PetApi.md
@@ -13,6 +13,7 @@ All URIs are relative to *http://petstore.swagger.io:80/v2*
 | [**UpdatePetWithForm**](PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data |
 | [**UploadFile**](PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image |
 | [**UploadFileWithRequiredFile**](PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required) |
+| [**UploadFiles**](PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images |
 
 <a id="addpet"></a>
 # **AddPet**
@@ -341,3 +342,38 @@ uploads an image (required)
 
 [[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
 
+<a id="uploadfiles"></a>
+# **UploadFiles**
+> ApiResponse UploadFiles (List<System.IO.Stream> files, long petId)
+
+uploads an images
+
+
+### Parameters
+
+| Name | Type | Description | Notes |
+|------|------|-------------|-------|
+| **files** | **List&lt;System.IO.Stream&gt;** |  |  |
+| **petId** | **long** | ID of pet to update |  |
+
+### Return type
+
+[**ApiResponse**](ApiResponse.md)
+
+### Authorization
+
+[petstore_auth](../README.md#petstore_auth)
+
+### HTTP request headers
+
+ - **Content-Type**: multipart/form-data
+ - **Accept**: application/json
+
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **200** | successful operation |  -  |
+
+[[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
+
diff --git a/samples/client/petstore/csharp/generichost/net9/SourceGeneration/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs b/samples/client/petstore/csharp/generichost/net9/SourceGeneration/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
index 406dbc964a6d..d207bb93dc69 100644
--- a/samples/client/petstore/csharp/generichost/net9/SourceGeneration/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/net9/SourceGeneration/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
@@ -196,7 +196,7 @@ public async Task TestEndpointParametersAsyncTest()
             string patternWithoutDelimiter = default!;
             byte[] varByte = default!;
             double varDouble = default!;
-            Client.Option<System.IO.Stream> binary = default!;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> binary = default!;
             Client.Option<string> callback = default!;
             Client.Option<DateOnly> date = default!;
             Client.Option<DateTime> dateTime = default!;
diff --git a/samples/client/petstore/csharp/generichost/net9/SourceGeneration/src/Org.OpenAPITools.Test/Api/PetApiTests.cs b/samples/client/petstore/csharp/generichost/net9/SourceGeneration/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
index 49e7b21b53c2..6bb1f953987c 100644
--- a/samples/client/petstore/csharp/generichost/net9/SourceGeneration/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/net9/SourceGeneration/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
@@ -137,7 +137,7 @@ public async Task UploadFileAsyncTest()
         {
             long petId = default!;
             Client.Option<string> additionalMetadata = default!;
-            Client.Option<System.IO.Stream> file = default!;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> file = default!;
             var response = await _instance.UploadFileAsync(petId, additionalMetadata, file);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
@@ -150,11 +150,24 @@ public async Task UploadFileAsyncTest()
         public async Task UploadFileWithRequiredFileAsyncTest()
         {
             long petId = default!;
-            System.IO.Stream requiredFile = default!;
+            Org.OpenAPITools.Client.FileParameter requiredFile = default!;
             Client.Option<string> additionalMetadata = default!;
             var response = await _instance.UploadFileWithRequiredFileAsync(petId, requiredFile, additionalMetadata);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
         }
+
+        /// <summary>
+        /// Test UploadFiles
+        /// </summary>
+        [Fact (Skip = "not implemented")]
+        public async Task UploadFilesAsyncTest()
+        {
+            List<Org.OpenAPITools.Client.FileParameter> files = default!;
+            long petId = default!;
+            var response = await _instance.UploadFilesAsync(files, petId);
+            var model = response.Ok();
+            Assert.IsType<ApiResponse>(model);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/net9/SourceGeneration/src/Org.OpenAPITools/Api/DefaultApi.cs b/samples/client/petstore/csharp/generichost/net9/SourceGeneration/src/Org.OpenAPITools/Api/DefaultApi.cs
index 2391c7e1ee03..46b798fe32ca 100644
--- a/samples/client/petstore/csharp/generichost/net9/SourceGeneration/src/Org.OpenAPITools/Api/DefaultApi.cs
+++ b/samples/client/petstore/csharp/generichost/net9/SourceGeneration/src/Org.OpenAPITools/Api/DefaultApi.cs
@@ -766,15 +766,12 @@ public async Task<IGetCountryApiResponse> GetCountryAsync(string country, System
                         ? "/country"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/country");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("country", ClientUtils.ParameterToString(country)));
 
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
-
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("country", ClientUtils.ParameterToString(country)));
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
 
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -782,11 +779,6 @@ public async Task<IGetCountryApiResponse> GetCountryAsync(string country, System
                         "application/x-www-form-urlencoded"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/net9/SourceGeneration/src/Org.OpenAPITools/Api/FakeApi.cs b/samples/client/petstore/csharp/generichost/net9/SourceGeneration/src/Org.OpenAPITools/Api/FakeApi.cs
index 262a94ef2520..54a1c8c85360 100644
--- a/samples/client/petstore/csharp/generichost/net9/SourceGeneration/src/Org.OpenAPITools/Api/FakeApi.cs
+++ b/samples/client/petstore/csharp/generichost/net9/SourceGeneration/src/Org.OpenAPITools/Api/FakeApi.cs
@@ -332,7 +332,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -356,7 +356,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>?&gt;</returns>
-        Task<ITestEndpointParametersApiResponse?> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse?> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// To test enum parameters
@@ -4082,7 +4082,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<System.IO.Stream> binary, ref Option<string> callback, ref Option<DateOnly> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
+        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<Org.OpenAPITools.Client.FileParameter> binary, ref Option<string> callback, ref Option<DateOnly> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
 
         /// <summary>
         /// Validates the request parameters
@@ -4094,7 +4094,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="password"></param>
         /// <param name="varString"></param>
         /// <returns></returns>
-        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<System.IO.Stream> binary, Option<string> callback, Option<string> password, Option<string> varString)
+        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<string> password, Option<string> varString)
         {
             if (patternWithoutDelimiter == null)
                 throw new ArgumentNullException(nameof(patternWithoutDelimiter));
@@ -4133,7 +4133,7 @@ private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLog = false;
             AfterTestEndpointParameters(ref suppressDefaultLog, apiResponseLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4160,7 +4160,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -4182,7 +4182,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorTestEndpointParameters(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4211,7 +4211,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateOnly> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트  Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -4232,7 +4232,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse?> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse?> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -4264,7 +4264,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateOnly> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -4283,51 +4283,48 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         ? "/fake"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("number", ClientUtils.ParameterToString(number)));
 
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("pattern_without_delimiter", ClientUtils.ParameterToString(patternWithoutDelimiter)));
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("byte", ClientUtils.ParameterToString(varByte)));
 
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("number", ClientUtils.ParameterToString(number)));
-
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("pattern_without_delimiter", ClientUtils.ParameterToString(patternWithoutDelimiter)));
-
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("byte", ClientUtils.ParameterToString(varByte)));
-
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("double", ClientUtils.ParameterToString(varDouble)));
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("double", ClientUtils.ParameterToString(varDouble)));
 
                     if (binary.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(binary.Value));
+                        throw new NotSupportedException("File parameters cannot be sent with application/x-www-form-urlencoded. Change the operation's content type to multipart/form-data.");
 
                     if (callback.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("callback", ClientUtils.ParameterToString(callback.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("callback", ClientUtils.ParameterToString(callback.Value)));
 
                     if (date.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("date", ClientUtils.ParameterToString(date.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("date", ClientUtils.ParameterToString(date.Value)));
 
                     if (dateTime.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("dateTime", ClientUtils.ParameterToString(dateTime.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("dateTime", ClientUtils.ParameterToString(dateTime.Value)));
 
                     if (int32.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("int32", ClientUtils.ParameterToString(int32.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("int32", ClientUtils.ParameterToString(int32.Value)));
 
                     if (int64.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("int64", ClientUtils.ParameterToString(int64.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("int64", ClientUtils.ParameterToString(int64.Value)));
 
                     if (integer.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("integer", ClientUtils.ParameterToString(integer.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("integer", ClientUtils.ParameterToString(integer.Value)));
 
                     if (password.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("password", ClientUtils.ParameterToString(password.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("password", ClientUtils.ParameterToString(password.Value)));
 
                     if (varFloat.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("float", ClientUtils.ParameterToString(varFloat.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("float", ClientUtils.ParameterToString(varFloat.Value)));
 
                     if (varString.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("string", ClientUtils.ParameterToString(varString.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("string", ClientUtils.ParameterToString(varString.Value)));
+
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -4342,11 +4339,6 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         "application/x-www-form-urlencoded"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -4639,17 +4631,16 @@ public async Task<ITestEnumParametersApiResponse> TestEnumParametersAsync(Option
                     if (enumHeaderStringArray.IsSet)
                         httpRequestMessageLocalVar.Headers.Add("enum_header_string_array", ClientUtils.ParameterToString(enumHeaderStringArray.Value));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
-
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (enumFormString.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("enum_form_string", ClientUtils.ParameterToString(enumFormString.Value)));
+                    if (enumFormString.IsSet)
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("enum_form_string", ClientUtils.ParameterToString(enumFormString.Value)));
 
                     if (enumFormStringArray.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("enum_form_string_array", ClientUtils.ParameterToString(enumFormStringArray.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("enum_form_string_array", ClientUtils.ParameterToString(enumFormStringArray.Value)));
+
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
 
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -4657,11 +4648,6 @@ public async Task<ITestEnumParametersApiResponse> TestEnumParametersAsync(Option
                         "application/x-www-form-urlencoded"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Get;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -5548,17 +5534,14 @@ public async Task<ITestJsonFormDataApiResponse> TestJsonFormDataAsync(string par
                         ? "/fake/jsonFormData"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/jsonFormData");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("param", ClientUtils.ParameterToString(param)));
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
+                    formParameterLocalVars.Add(new KeyValuePair<string, string?>("param2", ClientUtils.ParameterToString(param2)));
 
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("param", ClientUtils.ParameterToString(param)));
-
-                    formParameterLocalVars.Add(new KeyValuePair<string?, string?>("param2", ClientUtils.ParameterToString(param2)));
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
 
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -5566,11 +5549,6 @@ public async Task<ITestJsonFormDataApiResponse> TestJsonFormDataAsync(string par
                         "application/x-www-form-urlencoded"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Get;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/net9/SourceGeneration/src/Org.OpenAPITools/Api/PetApi.cs b/samples/client/petstore/csharp/generichost/net9/SourceGeneration/src/Org.OpenAPITools/Api/PetApi.cs
index 2d7e4dab0b84..c5de9cd55ad1 100644
--- a/samples/client/petstore/csharp/generichost/net9/SourceGeneration/src/Org.OpenAPITools/Api/PetApi.cs
+++ b/samples/client/petstore/csharp/generichost/net9/SourceGeneration/src/Org.OpenAPITools/Api/PetApi.cs
@@ -218,7 +218,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image
@@ -231,7 +231,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>?&gt;</returns>
-        Task<IUploadFileApiResponse?> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse?> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -245,7 +245,7 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -258,7 +258,32 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>?&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse?> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse?> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>?&gt;</returns>
+        Task<IUploadFilesApiResponse?> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
     }
 
     /// <summary>
@@ -417,6 +442,18 @@ public interface IUploadFileWithRequiredFileApiResponse : Org.OpenAPITools.Clien
         bool IsOk { get; }
     }
 
+    /// <summary>
+    /// The <see cref="IUploadFilesApiResponse"/>
+    /// </summary>
+    public interface IUploadFilesApiResponse : Org.OpenAPITools.Client.IApiResponse, IOk<Org.OpenAPITools.Model.ApiResponse?>
+    {
+        /// <summary>
+        /// Returns true if the response is 200 Ok
+        /// </summary>
+        /// <returns></returns>
+        bool IsOk { get; }
+    }
+
     /// <summary>
     /// Represents a collection of functions to interact with the API endpoints
     /// </summary>
@@ -601,6 +638,26 @@ internal void ExecuteOnErrorUploadFileWithRequiredFile(Exception exception)
         {
             OnErrorUploadFileWithRequiredFile?.Invoke(this, new ExceptionEventArgs(exception));
         }
+
+        /// <summary>
+        /// The event raised after the server response
+        /// </summary>
+        public event EventHandler<ApiResponseEventArgs>? OnUploadFiles;
+
+        /// <summary>
+        /// The event raised after an error querying the server
+        /// </summary>
+        public event EventHandler<ExceptionEventArgs>? OnErrorUploadFiles;
+
+        internal void ExecuteOnUploadFiles(PetApi.UploadFilesApiResponse apiResponse)
+        {
+            OnUploadFiles?.Invoke(this, new ApiResponseEventArgs(apiResponse));
+        }
+
+        internal void ExecuteOnErrorUploadFiles(Exception exception)
+        {
+            OnErrorUploadFiles?.Invoke(this, new ExceptionEventArgs(exception));
+        }
     }
 
     /// <summary>
@@ -2332,17 +2389,16 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (name.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("name", ClientUtils.ParameterToString(name.Value)));
+                    if (name.IsSet)
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("name", ClientUtils.ParameterToString(name.Value)));
 
                     if (status.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("status", ClientUtils.ParameterToString(status.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("status", ClientUtils.ParameterToString(status.Value)));
+
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -2357,11 +2413,6 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         "application/x-www-form-urlencoded"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = HttpMethod.Post;
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -2461,7 +2512,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<System.IO.Stream> file);
+        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Validates the request parameters
@@ -2469,7 +2520,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
         /// <returns></returns>
-        private void ValidateUploadFile(Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void ValidateUploadFile(Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             if (additionalMetadata.IsSet && additionalMetadata.Value == null)
                 throw new ArgumentNullException(nameof(additionalMetadata));
@@ -2485,7 +2536,7 @@ private void ValidateUploadFile(Option<string> additionalMetadata, Option<System
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLog = false;
             AfterUploadFile(ref suppressDefaultLog, apiResponseLocalVar, petId, additionalMetadata, file);
@@ -2501,7 +2552,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2512,7 +2563,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, additionalMetadata, file);
@@ -2530,7 +2581,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// uploads an image 
@@ -2540,7 +2591,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse?> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse?> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2561,7 +2612,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2581,17 +2632,23 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImage");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (additionalMetadata.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
+                    if (additionalMetadata.IsSet)
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
 
                     if (file.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(file.Value));
+                    {
+                        var streamContentLocalVar = new StreamContent(file.Value.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "file", file.Value.FileName ?? "file");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -2606,11 +2663,6 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         "multipart/form-data"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json"
                     };
@@ -2751,7 +2803,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFileWithRequiredFile(ref long petId, ref System.IO.Stream requiredFile, ref Option<string> additionalMetadata);
+        partial void FormatUploadFileWithRequiredFile(ref long petId, ref Org.OpenAPITools.Client.FileParameter requiredFile, ref Option<string> additionalMetadata);
 
         /// <summary>
         /// Validates the request parameters
@@ -2759,7 +2811,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
         /// <returns></returns>
-        private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void ValidateUploadFileWithRequiredFile(Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             if (requiredFile == null)
                 throw new ArgumentNullException(nameof(requiredFile));
@@ -2775,7 +2827,7 @@ private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, O
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLog = false;
             AfterUploadFileWithRequiredFile(ref suppressDefaultLog, apiResponseLocalVar, petId, requiredFile, additionalMetadata);
@@ -2791,7 +2843,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2802,7 +2854,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFileWithRequiredFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, requiredFile, additionalMetadata);
@@ -2820,7 +2872,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// uploads an image (required) 
@@ -2830,7 +2882,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse?> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse?> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2851,7 +2903,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2871,16 +2923,22 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/{petId}/uploadImageWithRequiredFile");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
-                    List<KeyValuePair<string?, string?>> formParameterLocalVars = new List<KeyValuePair<string?, string?>>();
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    multipartContentLocalVar.Add(new StreamContent(requiredFile));
+                    {
+                        var streamContentLocalVar = new StreamContent(requiredFile.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "requiredFile", requiredFile.FileName ?? "requiredFile");
+                    }
 
                     if (additionalMetadata.IsSet)
-                        formParameterLocalVars.Add(new KeyValuePair<string?, string?>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
+                        formParameterLocalVars.Add(new KeyValuePair<string, string?>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -2895,11 +2953,6 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         "multipart/form-data"
                     };
 
-                    string? contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json",
                         "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
@@ -3040,5 +3093,283 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
 
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
+
+        partial void FormatUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files, ref long petId);
+
+        /// <summary>
+        /// Validates the request parameters
+        /// </summary>
+        /// <param name="files"></param>
+        /// <returns></returns>
+        private void ValidateUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files)
+        {
+            if (files == null)
+                throw new ArgumentNullException(nameof(files));
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void AfterUploadFilesDefaultImplementation(IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLog = false;
+            AfterUploadFiles(ref suppressDefaultLog, apiResponseLocalVar, files, petId);
+            if (!suppressDefaultLog)
+                Logger.LogInformation("{0,-9} | {1} | {2}", (apiResponseLocalVar.DownloadedAt - apiResponseLocalVar.RequestedAt).TotalSeconds, apiResponseLocalVar.StatusCode, apiResponseLocalVar.Path);
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="suppressDefaultLog"></param>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void AfterUploadFiles(ref bool suppressDefaultLog, IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// Logs exceptions that occur while retrieving the server response
+        /// </summary>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void OnErrorUploadFilesDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLogLocalVar = false;
+            OnErrorUploadFiles(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, files, petId);
+            if (!suppressDefaultLogLocalVar)
+                Logger.LogError(exceptionLocalVar, "An error occurred while sending the request to the server.");
+        }
+
+        /// <summary>
+        /// A partial method that gives developers a way to provide customized exception handling
+        /// </summary>
+        /// <param name="suppressDefaultLogLocalVar"></param>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void OnErrorUploadFiles(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse?> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            try
+            {
+                return await UploadFilesAsync(files, petId, cancellationToken).ConfigureAwait(false);
+            }
+            catch (Exception)
+            {
+                return null;
+            }
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            UriBuilder uriBuilderLocalVar = new UriBuilder();
+
+            try
+            {
+                ValidateUploadFiles(files);
+
+                FormatUploadFiles(files, ref petId);
+
+                using (HttpRequestMessage httpRequestMessageLocalVar = new HttpRequestMessage())
+                {
+                    uriBuilderLocalVar.Host = HttpClient.BaseAddress!.Host;
+                    uriBuilderLocalVar.Port = HttpClient.BaseAddress.Port;
+                    uriBuilderLocalVar.Scheme = HttpClient.BaseAddress.Scheme;
+                    uriBuilderLocalVar.Path = HttpClient.BaseAddress.AbsolutePath == "/"
+                        ? "/pet/{petId}/uploadImages"
+                        : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImages");
+                    uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
+
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
+
+                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+
+                    List<KeyValuePair<string, string?>> formParameterLocalVars = new List<KeyValuePair<string, string?>>();
+
+                    foreach (Org.OpenAPITools.Client.FileParameter fileParameterLocalVar in files)
+                    {
+                        var streamContentLocalVar = new StreamContent(fileParameterLocalVar.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "files", fileParameterLocalVar.FileName ?? "files");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
+
+                    List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
+                    httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
+
+                    OAuthToken oauthTokenLocalVar1 = (OAuthToken) await OauthTokenProvider.GetAsync(cancellation: cancellationToken).ConfigureAwait(false);
+
+                    tokenBaseLocalVars.Add(oauthTokenLocalVar1);
+
+                    oauthTokenLocalVar1.UseInHeader(httpRequestMessageLocalVar, "");
+
+                    string[] contentTypes = new string[] {
+                        "multipart/form-data"
+                    };
+
+                    string[] acceptLocalVars = new string[] {
+                        "application/json"
+                    };
+
+                    IEnumerable<MediaTypeWithQualityHeaderValue> acceptHeaderValuesLocalVar = ClientUtils.SelectHeaderAcceptArray(acceptLocalVars);
+
+                    foreach (var acceptLocalVar in acceptHeaderValuesLocalVar)
+                        httpRequestMessageLocalVar.Headers.Accept.Add(acceptLocalVar);
+
+                    httpRequestMessageLocalVar.Method = HttpMethod.Post;
+
+                    DateTime requestedAtLocalVar = DateTime.UtcNow;
+
+                    using (HttpResponseMessage httpResponseMessageLocalVar = await HttpClient.SendAsync(httpRequestMessageLocalVar, cancellationToken).ConfigureAwait(false))
+                    {
+                        ILogger<UploadFilesApiResponse> apiResponseLoggerLocalVar = LoggerFactory.CreateLogger<UploadFilesApiResponse>();
+                        UploadFilesApiResponse apiResponseLocalVar;
+
+                        switch ((int)httpResponseMessageLocalVar.StatusCode) {
+                            default: {
+                                string responseContentLocalVar = await httpResponseMessageLocalVar.Content.ReadAsStringAsync(cancellationToken).ConfigureAwait(false);
+                                apiResponseLocalVar = new(apiResponseLoggerLocalVar, httpRequestMessageLocalVar, httpResponseMessageLocalVar, responseContentLocalVar, "/pet/{petId}/uploadImages", requestedAtLocalVar, _jsonSerializerOptions);
+
+                                break;
+                            }
+                        }
+
+                        AfterUploadFilesDefaultImplementation(apiResponseLocalVar, files, petId);
+
+                        Events.ExecuteOnUploadFiles(apiResponseLocalVar);
+
+                        if (apiResponseLocalVar.StatusCode == (HttpStatusCode) 429)
+                            foreach(TokenBase tokenBaseLocalVar in tokenBaseLocalVars)
+                                tokenBaseLocalVar.BeginRateLimit();
+
+                        return apiResponseLocalVar;
+                    }
+                }
+            }
+            catch(Exception e)
+            {
+                OnErrorUploadFilesDefaultImplementation(e, "/pet/{petId}/uploadImages", uriBuilderLocalVar.Path, files, petId);
+                Events.ExecuteOnErrorUploadFiles(e);
+                throw;
+            }
+        }
+
+        /// <summary>
+        /// The <see cref="UploadFilesApiResponse"/>
+        /// </summary>
+        public partial class UploadFilesApiResponse : Org.OpenAPITools.Client.ApiResponse, IUploadFilesApiResponse
+        {
+            /// <summary>
+            /// The logger
+            /// </summary>
+            public ILogger<UploadFilesApiResponse> Logger { get; }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="rawContent"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, string rawContent, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, rawContent, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="contentStream"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, System.IO.Stream contentStream, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, contentStream, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            partial void OnCreated(global::System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage);
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public bool IsOk => 200 == (int)StatusCode;
+
+            /// <summary>
+            /// Deserializes the response if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public Org.OpenAPITools.Model.ApiResponse? Ok()
+            {
+                // This logic may be modified with the AsModel.mustache template
+                return IsOk
+                    ? System.Text.Json.JsonSerializer.Deserialize<Org.OpenAPITools.Model.ApiResponse>(RawContent, _jsonSerializerOptions)
+                    : null;
+            }
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok and the deserialized response is not null
+            /// </summary>
+            /// <param name="result"></param>
+            /// <returns></returns>
+            public bool TryOk([NotNullWhen(true)]out Org.OpenAPITools.Model.ApiResponse? result)
+            {
+                result = null;
+
+                try
+                {
+                    result = Ok();
+                } catch (Exception e)
+                {
+                    OnDeserializationErrorDefaultImplementation(e, (HttpStatusCode)200);
+                }
+
+                return result != null;
+            }
+
+            private void OnDeserializationErrorDefaultImplementation(Exception exception, HttpStatusCode httpStatusCode)
+            {
+                bool suppressDefaultLog = false;
+                OnDeserializationError(ref suppressDefaultLog, exception, httpStatusCode);
+                if (!suppressDefaultLog)
+                    Logger.LogError(exception, "An error occurred while deserializing the {code} response.", httpStatusCode);
+            }
+
+            partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/net9/SourceGeneration/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net9/SourceGeneration/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..77779fe7d75a
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net9/SourceGeneration/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,42 @@
+// <auto-generated>
+/*
+ * OpenAPI Petstore
+ *
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+#nullable enable
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string? FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string? fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/net9/UseDateTimeForDate/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/net9/UseDateTimeForDate/.openapi-generator/FILES
index 5abbcf46f35c..e28da391730f 100644
--- a/samples/client/petstore/csharp/generichost/net9/UseDateTimeForDate/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/net9/UseDateTimeForDate/.openapi-generator/FILES
@@ -21,6 +21,7 @@ src/Org.OpenAPITools/Client/CookieContainer.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/JsonSerializerOptionsProvider.cs
 src/Org.OpenAPITools/Client/Option.cs
diff --git a/samples/client/petstore/csharp/generichost/net9/UseDateTimeForDate/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/net9/UseDateTimeForDate/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..11da1d925144
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/net9/UseDateTimeForDate/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,42 @@
+// <auto-generated>
+/*
+ * OpenAPI Dates
+ *
+ * Thic spec contains endpoints with dates in different formats
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+#nullable enable
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string? FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string? fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/generichost/standard2.0/Petstore/.openapi-generator/FILES b/samples/client/petstore/csharp/generichost/standard2.0/Petstore/.openapi-generator/FILES
index a6635c9d8351..82501a149e01 100644
--- a/samples/client/petstore/csharp/generichost/standard2.0/Petstore/.openapi-generator/FILES
+++ b/samples/client/petstore/csharp/generichost/standard2.0/Petstore/.openapi-generator/FILES
@@ -138,6 +138,7 @@ src/Org.OpenAPITools/Client/CookieContainer.cs
 src/Org.OpenAPITools/Client/DateTimeJsonConverter.cs
 src/Org.OpenAPITools/Client/DateTimeNullableJsonConverter.cs
 src/Org.OpenAPITools/Client/ExceptionEventArgs.cs
+src/Org.OpenAPITools/Client/FileParameter.cs
 src/Org.OpenAPITools/Client/HostConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
 src/Org.OpenAPITools/Client/HttpSigningToken.cs
diff --git a/samples/client/petstore/csharp/generichost/standard2.0/Petstore/api/openapi.yaml b/samples/client/petstore/csharp/generichost/standard2.0/Petstore/api/openapi.yaml
index d8106a5755fc..ca451f3fb832 100644
--- a/samples/client/petstore/csharp/generichost/standard2.0/Petstore/api/openapi.yaml
+++ b/samples/client/petstore/csharp/generichost/standard2.0/Petstore/api/openapi.yaml
@@ -331,6 +331,40 @@ paths:
       summary: uploads an image
       tags:
       - pet
+  /pet/{petId}/uploadImages:
+    post:
+      description: ""
+      operationId: uploadFiles
+      parameters:
+      - description: ID of pet to update
+        explode: false
+        in: path
+        name: petId
+        required: true
+        schema:
+          format: int64
+          type: integer
+        style: simple
+      requestBody:
+        content:
+          multipart/form-data:
+            schema:
+              $ref: "#/components/schemas/uploadFiles_request"
+        required: true
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ApiResponse"
+          description: successful operation
+      security:
+      - petstore_auth:
+        - write:pets
+        - read:pets
+      summary: uploads an images
+      tags:
+      - pet
   /store/inventory:
     get:
       description: Returns a map of status codes to quantities
@@ -2924,6 +2958,16 @@ components:
           format: binary
           type: string
       type: object
+    uploadFiles_request:
+      properties:
+        files:
+          items:
+            format: binary
+            type: string
+          type: array
+      required:
+      - files
+      type: object
     testEnumParameters_request:
       properties:
         enum_form_string_array:
diff --git a/samples/client/petstore/csharp/generichost/standard2.0/Petstore/docs/apis/PetApi.md b/samples/client/petstore/csharp/generichost/standard2.0/Petstore/docs/apis/PetApi.md
index 2826ea00f728..b42ee516b313 100644
--- a/samples/client/petstore/csharp/generichost/standard2.0/Petstore/docs/apis/PetApi.md
+++ b/samples/client/petstore/csharp/generichost/standard2.0/Petstore/docs/apis/PetApi.md
@@ -13,6 +13,7 @@ All URIs are relative to *http://petstore.swagger.io:80/v2*
 | [**UpdatePetWithForm**](PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data |
 | [**UploadFile**](PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image |
 | [**UploadFileWithRequiredFile**](PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required) |
+| [**UploadFiles**](PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images |
 
 <a id="addpet"></a>
 # **AddPet**
@@ -341,3 +342,38 @@ uploads an image (required)
 
 [[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
 
+<a id="uploadfiles"></a>
+# **UploadFiles**
+> ApiResponse UploadFiles (List<System.IO.Stream> files, long petId)
+
+uploads an images
+
+
+### Parameters
+
+| Name | Type | Description | Notes |
+|------|------|-------------|-------|
+| **files** | **List&lt;System.IO.Stream&gt;** |  |  |
+| **petId** | **long** | ID of pet to update |  |
+
+### Return type
+
+[**ApiResponse**](ApiResponse.md)
+
+### Authorization
+
+[petstore_auth](../README.md#petstore_auth)
+
+### HTTP request headers
+
+ - **Content-Type**: multipart/form-data
+ - **Accept**: application/json
+
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **200** | successful operation |  -  |
+
+[[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
+
diff --git a/samples/client/petstore/csharp/generichost/standard2.0/Petstore/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs b/samples/client/petstore/csharp/generichost/standard2.0/Petstore/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
index ce85f85778ef..6420b47bc8b4 100644
--- a/samples/client/petstore/csharp/generichost/standard2.0/Petstore/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/standard2.0/Petstore/src/Org.OpenAPITools.Test/Api/FakeApiTests.cs
@@ -196,7 +196,7 @@ public async Task TestEndpointParametersAsyncTest()
             string patternWithoutDelimiter = default;
             byte[] varByte = default;
             double varDouble = default;
-            Client.Option<System.IO.Stream> binary = default;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> binary = default;
             Client.Option<string> callback = default;
             Client.Option<DateTime> date = default;
             Client.Option<DateTime> dateTime = default;
diff --git a/samples/client/petstore/csharp/generichost/standard2.0/Petstore/src/Org.OpenAPITools.Test/Api/PetApiTests.cs b/samples/client/petstore/csharp/generichost/standard2.0/Petstore/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
index 215e88093797..e9b05337bb59 100644
--- a/samples/client/petstore/csharp/generichost/standard2.0/Petstore/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
+++ b/samples/client/petstore/csharp/generichost/standard2.0/Petstore/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
@@ -137,7 +137,7 @@ public async Task UploadFileAsyncTest()
         {
             long petId = default;
             Client.Option<string> additionalMetadata = default;
-            Client.Option<System.IO.Stream> file = default;
+            Client.Option<Org.OpenAPITools.Client.FileParameter> file = default;
             var response = await _instance.UploadFileAsync(petId, additionalMetadata, file);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
@@ -150,11 +150,24 @@ public async Task UploadFileAsyncTest()
         public async Task UploadFileWithRequiredFileAsyncTest()
         {
             long petId = default;
-            System.IO.Stream requiredFile = default;
+            Org.OpenAPITools.Client.FileParameter requiredFile = default;
             Client.Option<string> additionalMetadata = default;
             var response = await _instance.UploadFileWithRequiredFileAsync(petId, requiredFile, additionalMetadata);
             var model = response.Ok();
             Assert.IsType<ApiResponse>(model);
         }
+
+        /// <summary>
+        /// Test UploadFiles
+        /// </summary>
+        [Fact (Skip = "not implemented")]
+        public async Task UploadFilesAsyncTest()
+        {
+            List<Org.OpenAPITools.Client.FileParameter> files = default;
+            long petId = default;
+            var response = await _instance.UploadFilesAsync(files, petId);
+            var model = response.Ok();
+            Assert.IsType<ApiResponse>(model);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/standard2.0/Petstore/src/Org.OpenAPITools/Api/DefaultApi.cs b/samples/client/petstore/csharp/generichost/standard2.0/Petstore/src/Org.OpenAPITools/Api/DefaultApi.cs
index 8f794c9ca7c8..a37b13115c90 100644
--- a/samples/client/petstore/csharp/generichost/standard2.0/Petstore/src/Org.OpenAPITools/Api/DefaultApi.cs
+++ b/samples/client/petstore/csharp/generichost/standard2.0/Petstore/src/Org.OpenAPITools/Api/DefaultApi.cs
@@ -762,27 +762,19 @@ public async Task<IGetCountryApiResponse> GetCountryAsync(string country, System
                         ? "/country"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/country");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("country", ClientUtils.ParameterToString(country)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = new HttpMethod("POST");
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/standard2.0/Petstore/src/Org.OpenAPITools/Api/FakeApi.cs b/samples/client/petstore/csharp/generichost/standard2.0/Petstore/src/Org.OpenAPITools/Api/FakeApi.cs
index 0d878f64abf2..33cecd82aa0a 100644
--- a/samples/client/petstore/csharp/generichost/standard2.0/Petstore/src/Org.OpenAPITools/Api/FakeApi.cs
+++ b/samples/client/petstore/csharp/generichost/standard2.0/Petstore/src/Org.OpenAPITools/Api/FakeApi.cs
@@ -329,7 +329,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -353,7 +353,7 @@ public interface IFakeApi : IApi
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// To test enum parameters
@@ -4070,7 +4070,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<System.IO.Stream> binary, ref Option<string> callback, ref Option<DateTime> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
+        partial void FormatTestEndpointParameters(ref decimal number, ref string patternWithoutDelimiter, ref byte[] varByte, ref double varDouble, ref Option<Org.OpenAPITools.Client.FileParameter> binary, ref Option<string> callback, ref Option<DateTime> date, ref Option<DateTime> dateTime, ref Option<int> int32, ref Option<long> int64, ref Option<int> integer, ref Option<string> password, ref Option<float> varFloat, ref Option<string> varString);
 
         /// <summary>
         /// Validates the request parameters
@@ -4082,7 +4082,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="password"></param>
         /// <param name="varString"></param>
         /// <returns></returns>
-        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<System.IO.Stream> binary, Option<string> callback, Option<string> password, Option<string> varString)
+        private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte[] varByte, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<string> password, Option<string> varString)
         {
             if (patternWithoutDelimiter == null)
                 throw new ArgumentNullException(nameof(patternWithoutDelimiter));
@@ -4121,7 +4121,7 @@ private void ValidateTestEndpointParameters(string patternWithoutDelimiter, byte
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLog = false;
             AfterTestEndpointParameters(ref suppressDefaultLog, apiResponseLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4148,7 +4148,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void AfterTestEndpointParameters(ref bool suppressDefaultLog, ITestEndpointParametersApiResponse apiResponseLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -4170,7 +4170,7 @@ private void AfterTestEndpointParametersDefaultImplementation(ITestEndpointParam
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
+        private void OnErrorTestEndpointParametersDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorTestEndpointParameters(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, number, patternWithoutDelimiter, varByte, varDouble, binary, callback, date, dateTime, int32, int64, integer, password, varFloat, varString);
@@ -4199,7 +4199,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="password"></param>
         /// <param name="varFloat"></param>
         /// <param name="varString"></param>
-        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
+        partial void OnErrorTestEndpointParameters(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary, Option<string> callback, Option<DateTime> date, Option<DateTime> dateTime, Option<int> int32, Option<long> int64, Option<int> integer, Option<string> password, Option<float> varFloat, Option<string> varString);
 
         /// <summary>
         /// Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트  Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
@@ -4220,7 +4220,7 @@ private void OnErrorTestEndpointParametersDefaultImplementation(Exception except
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDefaultAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -4252,7 +4252,7 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersOrDe
         /// <param name="varString">None (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ITestEndpointParametersApiResponse"/>&gt;</returns>
-        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<System.IO.Stream> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsync(decimal number, string patternWithoutDelimiter, byte[] varByte, double varDouble, Option<Org.OpenAPITools.Client.FileParameter> binary = default, Option<string> callback = default, Option<DateTime> date = default, Option<DateTime> dateTime = default, Option<int> int32 = default, Option<long> int64 = default, Option<int> integer = default, Option<string> password = default, Option<float> varFloat = default, Option<string> varString = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -4271,14 +4271,8 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         ? "/fake"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("number", ClientUtils.ParameterToString(number)));
 
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("pattern_without_delimiter", ClientUtils.ParameterToString(patternWithoutDelimiter)));
@@ -4288,7 +4282,7 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("double", ClientUtils.ParameterToString(varDouble)));
 
                     if (binary.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(binary.Value));
+                        throw new NotSupportedException("File parameters cannot be sent with application/x-www-form-urlencoded. Change the operation's content type to multipart/form-data.");
 
                     if (callback.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("callback", ClientUtils.ParameterToString(callback.Value)));
@@ -4317,6 +4311,9 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                     if (varString.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("string", ClientUtils.ParameterToString(varString.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -4330,11 +4327,6 @@ public async Task<ITestEndpointParametersApiResponse> TestEndpointParametersAsyn
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = new HttpMethod("POST");
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -4627,29 +4619,23 @@ public async Task<ITestEnumParametersApiResponse> TestEnumParametersAsync(Option
                     if (enumHeaderStringArray.IsSet)
                         httpRequestMessageLocalVar.Headers.Add("enum_header_string_array", ClientUtils.ParameterToString(enumHeaderStringArray.Value));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (enumFormString.IsSet)
+                    if (enumFormString.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("enum_form_string", ClientUtils.ParameterToString(enumFormString.Value)));
 
                     if (enumFormStringArray.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("enum_form_string_array", ClientUtils.ParameterToString(enumFormStringArray.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = new HttpMethod("GET");
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -5535,29 +5521,21 @@ public async Task<ITestJsonFormDataApiResponse> TestJsonFormDataAsync(string par
                         ? "/fake/jsonFormData"
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/jsonFormData");
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));
-
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("param", ClientUtils.ParameterToString(param)));
 
                     formParameterLocalVars.Add(new KeyValuePair<string, string>("param2", ClientUtils.ParameterToString(param2)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
                     string[] contentTypes = new string[] {
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = new HttpMethod("GET");
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
diff --git a/samples/client/petstore/csharp/generichost/standard2.0/Petstore/src/Org.OpenAPITools/Api/PetApi.cs b/samples/client/petstore/csharp/generichost/standard2.0/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
index 00c695ffd700..bbe2532cf740 100644
--- a/samples/client/petstore/csharp/generichost/standard2.0/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
+++ b/samples/client/petstore/csharp/generichost/standard2.0/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
@@ -215,7 +215,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image
@@ -228,7 +228,7 @@ public interface IPetApi : IApi
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -242,7 +242,7 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
 
         /// <summary>
         /// uploads an image (required)
@@ -255,7 +255,32 @@ public interface IPetApi : IApi
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        Task<IUploadFilesApiResponse> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default);
     }
 
     /// <summary>
@@ -414,6 +439,18 @@ public interface IUploadFileWithRequiredFileApiResponse : Org.OpenAPITools.Clien
         bool IsOk { get; }
     }
 
+    /// <summary>
+    /// The <see cref="IUploadFilesApiResponse"/>
+    /// </summary>
+    public interface IUploadFilesApiResponse : Org.OpenAPITools.Client.IApiResponse, IOk<Org.OpenAPITools.Model.ApiResponse>
+    {
+        /// <summary>
+        /// Returns true if the response is 200 Ok
+        /// </summary>
+        /// <returns></returns>
+        bool IsOk { get; }
+    }
+
     /// <summary>
     /// Represents a collection of functions to interact with the API endpoints
     /// </summary>
@@ -598,6 +635,26 @@ internal void ExecuteOnErrorUploadFileWithRequiredFile(Exception exception)
         {
             OnErrorUploadFileWithRequiredFile?.Invoke(this, new ExceptionEventArgs(exception));
         }
+
+        /// <summary>
+        /// The event raised after the server response
+        /// </summary>
+        public event EventHandler<ApiResponseEventArgs> OnUploadFiles;
+
+        /// <summary>
+        /// The event raised after an error querying the server
+        /// </summary>
+        public event EventHandler<ExceptionEventArgs> OnErrorUploadFiles;
+
+        internal void ExecuteOnUploadFiles(PetApi.UploadFilesApiResponse apiResponse)
+        {
+            OnUploadFiles?.Invoke(this, new ApiResponseEventArgs(apiResponse));
+        }
+
+        internal void ExecuteOnErrorUploadFiles(Exception exception)
+        {
+            OnErrorUploadFiles?.Invoke(this, new ExceptionEventArgs(exception));
+        }
     }
 
     /// <summary>
@@ -2325,18 +2382,17 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
-
-                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
-
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (name.IsSet)
+                    if (name.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("name", ClientUtils.ParameterToString(name.Value)));
 
                     if (status.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("status", ClientUtils.ParameterToString(status.Value)));
 
+                    if (formParameterLocalVars.Count > 0)
+                        httpRequestMessageLocalVar.Content = new FormUrlEncodedContent(formParameterLocalVars);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -2350,11 +2406,6 @@ public async Task<IUpdatePetWithFormApiResponse> UpdatePetWithFormAsync(long pet
                         "application/x-www-form-urlencoded"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     httpRequestMessageLocalVar.Method = new HttpMethod("POST");
 
                     DateTime requestedAtLocalVar = DateTime.UtcNow;
@@ -2454,7 +2505,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<System.IO.Stream> file);
+        partial void FormatUploadFile(ref long petId, ref Option<string> additionalMetadata, ref Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Validates the request parameters
@@ -2462,7 +2513,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
         /// <returns></returns>
-        private void ValidateUploadFile(Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void ValidateUploadFile(Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             if (additionalMetadata.IsSet && additionalMetadata.Value == null)
                 throw new ArgumentNullException(nameof(additionalMetadata));
@@ -2478,7 +2529,7 @@ private void ValidateUploadFile(Option<string> additionalMetadata, Option<System
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLog = false;
             AfterUploadFile(ref suppressDefaultLog, apiResponseLocalVar, petId, additionalMetadata, file);
@@ -2494,7 +2545,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void AfterUploadFile(ref bool suppressDefaultLog, IUploadFileApiResponse apiResponseLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2505,7 +2556,7 @@ private void AfterUploadFileDefaultImplementation(IUploadFileApiResponse apiResp
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file)
+        private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, additionalMetadata, file);
@@ -2523,7 +2574,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="petId"></param>
         /// <param name="additionalMetadata"></param>
         /// <param name="file"></param>
-        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<System.IO.Stream> file);
+        partial void OnErrorUploadFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Option<string> additionalMetadata, Option<Org.OpenAPITools.Client.FileParameter> file);
 
         /// <summary>
         /// uploads an image 
@@ -2533,7 +2584,7 @@ private void OnErrorUploadFileDefaultImplementation(Exception exceptionLocalVar,
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2554,7 +2605,7 @@ public async Task<IUploadFileApiResponse> UploadFileOrDefaultAsync(long petId, O
         /// <param name="file">file to upload (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<System.IO.Stream> file = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<string> additionalMetadata = default, Option<Org.OpenAPITools.Client.FileParameter> file = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2574,17 +2625,23 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImage");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    if (additionalMetadata.IsSet)
+                    if (additionalMetadata.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
 
                     if (file.IsSet)
-                        multipartContentLocalVar.Add(new StreamContent(file.Value));
+                    {
+                        var streamContentLocalVar = new StreamContent(file.Value.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "file", file.Value.FileName ?? "file");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
 
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
@@ -2599,11 +2656,6 @@ public async Task<IUploadFileApiResponse> UploadFileAsync(long petId, Option<str
                         "multipart/form-data"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json"
                     };
@@ -2743,7 +2795,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
 
-        partial void FormatUploadFileWithRequiredFile(ref long petId, ref System.IO.Stream requiredFile, ref Option<string> additionalMetadata);
+        partial void FormatUploadFileWithRequiredFile(ref long petId, ref Org.OpenAPITools.Client.FileParameter requiredFile, ref Option<string> additionalMetadata);
 
         /// <summary>
         /// Validates the request parameters
@@ -2751,7 +2803,7 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
         /// <returns></returns>
-        private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void ValidateUploadFileWithRequiredFile(Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             if (requiredFile == null)
                 throw new ArgumentNullException(nameof(requiredFile));
@@ -2767,7 +2819,7 @@ private void ValidateUploadFileWithRequiredFile(System.IO.Stream requiredFile, O
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLog = false;
             AfterUploadFileWithRequiredFile(ref suppressDefaultLog, apiResponseLocalVar, petId, requiredFile, additionalMetadata);
@@ -2783,7 +2835,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void AfterUploadFileWithRequiredFile(ref bool suppressDefaultLog, IUploadFileWithRequiredFileApiResponse apiResponseLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// Logs exceptions that occur while retrieving the server response
@@ -2794,7 +2846,7 @@ private void AfterUploadFileWithRequiredFileDefaultImplementation(IUploadFileWit
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata)
+        private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata)
         {
             bool suppressDefaultLogLocalVar = false;
             OnErrorUploadFileWithRequiredFile(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, petId, requiredFile, additionalMetadata);
@@ -2812,7 +2864,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="petId"></param>
         /// <param name="requiredFile"></param>
         /// <param name="additionalMetadata"></param>
-        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata);
+        partial void OnErrorUploadFileWithRequiredFile(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata);
 
         /// <summary>
         /// uploads an image (required) 
@@ -2822,7 +2874,7 @@ private void OnErrorUploadFileWithRequiredFileDefaultImplementation(Exception ex
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileOrDefaultAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             try
             {
@@ -2843,7 +2895,7 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="IUploadFileWithRequiredFileApiResponse"/>&gt;</returns>
-        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, System.IO.Stream requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
+        public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequiredFileAsync(long petId, Org.OpenAPITools.Client.FileParameter requiredFile, Option<string> additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default)
         {
             UriBuilder uriBuilderLocalVar = new UriBuilder();
 
@@ -2863,17 +2915,23 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/fake/{petId}/uploadImageWithRequiredFile");
                     uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
 
-                    MultipartContent multipartContentLocalVar = new MultipartContent();
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
 
                     httpRequestMessageLocalVar.Content = multipartContentLocalVar;
 
                     List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
 
-                    multipartContentLocalVar.Add(new FormUrlEncodedContent(formParameterLocalVars));                    multipartContentLocalVar.Add(new StreamContent(requiredFile));
+                    {
+                        var streamContentLocalVar = new StreamContent(requiredFile.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "requiredFile", requiredFile.FileName ?? "requiredFile");
+                    }
 
                     if (additionalMetadata.IsSet)
                         formParameterLocalVars.Add(new KeyValuePair<string, string>("additionalMetadata", ClientUtils.ParameterToString(additionalMetadata.Value)));
 
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
+
                     List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
                     httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
 
@@ -2887,11 +2945,6 @@ public async Task<IUploadFileWithRequiredFileApiResponse> UploadFileWithRequired
                         "multipart/form-data"
                     };
 
-                    string contentTypeLocalVar = ClientUtils.SelectHeaderContentType(contentTypes);
-
-                    if (contentTypeLocalVar != null && httpRequestMessageLocalVar.Content != null)
-                        httpRequestMessageLocalVar.Content.Headers.ContentType = new MediaTypeHeaderValue(contentTypeLocalVar);
-
                     string[] acceptLocalVars = new string[] {
                         "application/json",
                         "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
@@ -3031,5 +3084,282 @@ private void OnDeserializationErrorDefaultImplementation(Exception exception, Ht
 
             partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
         }
+
+        partial void FormatUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files, ref long petId);
+
+        /// <summary>
+        /// Validates the request parameters
+        /// </summary>
+        /// <param name="files"></param>
+        /// <returns></returns>
+        private void ValidateUploadFiles(List<Org.OpenAPITools.Client.FileParameter> files)
+        {
+            if (files == null)
+                throw new ArgumentNullException(nameof(files));
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void AfterUploadFilesDefaultImplementation(IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLog = false;
+            AfterUploadFiles(ref suppressDefaultLog, apiResponseLocalVar, files, petId);
+            if (!suppressDefaultLog)
+                Logger.LogInformation("{0,-9} | {1} | {2}", (apiResponseLocalVar.DownloadedAt - apiResponseLocalVar.RequestedAt).TotalSeconds, apiResponseLocalVar.StatusCode, apiResponseLocalVar.Path);
+        }
+
+        /// <summary>
+        /// Processes the server response
+        /// </summary>
+        /// <param name="suppressDefaultLog"></param>
+        /// <param name="apiResponseLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void AfterUploadFiles(ref bool suppressDefaultLog, IUploadFilesApiResponse apiResponseLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// Logs exceptions that occur while retrieving the server response
+        /// </summary>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        private void OnErrorUploadFilesDefaultImplementation(Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId)
+        {
+            bool suppressDefaultLogLocalVar = false;
+            OnErrorUploadFiles(ref suppressDefaultLogLocalVar, exceptionLocalVar, pathFormatLocalVar, pathLocalVar, files, petId);
+            if (!suppressDefaultLogLocalVar)
+                Logger.LogError(exceptionLocalVar, "An error occurred while sending the request to the server.");
+        }
+
+        /// <summary>
+        /// A partial method that gives developers a way to provide customized exception handling
+        /// </summary>
+        /// <param name="suppressDefaultLogLocalVar"></param>
+        /// <param name="exceptionLocalVar"></param>
+        /// <param name="pathFormatLocalVar"></param>
+        /// <param name="pathLocalVar"></param>
+        /// <param name="files"></param>
+        /// <param name="petId"></param>
+        partial void OnErrorUploadFiles(ref bool suppressDefaultLogLocalVar, Exception exceptionLocalVar, string pathFormatLocalVar, string pathLocalVar, List<Org.OpenAPITools.Client.FileParameter> files, long petId);
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse> UploadFilesOrDefaultAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            try
+            {
+                return await UploadFilesAsync(files, petId, cancellationToken).ConfigureAwait(false);
+            }
+            catch (Exception)
+            {
+                return null;
+            }
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="ApiException">Thrown when fails to make API call</exception>
+        /// <param name="files"></param>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns><see cref="Task"/>&lt;<see cref="IUploadFilesApiResponse"/>&gt;</returns>
+        public async Task<IUploadFilesApiResponse> UploadFilesAsync(List<Org.OpenAPITools.Client.FileParameter> files, long petId, System.Threading.CancellationToken cancellationToken = default)
+        {
+            UriBuilder uriBuilderLocalVar = new UriBuilder();
+
+            try
+            {
+                ValidateUploadFiles(files);
+
+                FormatUploadFiles(files, ref petId);
+
+                using (HttpRequestMessage httpRequestMessageLocalVar = new HttpRequestMessage())
+                {
+                    uriBuilderLocalVar.Host = HttpClient.BaseAddress.Host;
+                    uriBuilderLocalVar.Port = HttpClient.BaseAddress.Port;
+                    uriBuilderLocalVar.Scheme = HttpClient.BaseAddress.Scheme;
+                    uriBuilderLocalVar.Path = HttpClient.BaseAddress.AbsolutePath == "/"
+                        ? "/pet/{petId}/uploadImages"
+                        : string.Concat(HttpClient.BaseAddress.AbsolutePath, "/pet/{petId}/uploadImages");
+                    uriBuilderLocalVar.Path = uriBuilderLocalVar.Path.Replace("%7BpetId%7D", Uri.EscapeDataString(petId.ToString()));
+
+                    MultipartFormDataContent multipartContentLocalVar = new MultipartFormDataContent();
+
+                    httpRequestMessageLocalVar.Content = multipartContentLocalVar;
+
+                    List<KeyValuePair<string, string>> formParameterLocalVars = new List<KeyValuePair<string, string>>();
+
+                    foreach (Org.OpenAPITools.Client.FileParameter fileParameterLocalVar in files)
+                    {
+                        var streamContentLocalVar = new StreamContent(fileParameterLocalVar.Content);
+                        multipartContentLocalVar.Add(streamContentLocalVar, "files", fileParameterLocalVar.FileName ?? "files");
+                    }
+
+                    foreach (var formParamLocalVar in formParameterLocalVars)
+                        multipartContentLocalVar.Add(new StringContent(formParamLocalVar.Value ?? string.Empty), formParamLocalVar.Key);
+
+                    List<TokenBase> tokenBaseLocalVars = new List<TokenBase>();
+                    httpRequestMessageLocalVar.RequestUri = uriBuilderLocalVar.Uri;
+
+                    OAuthToken oauthTokenLocalVar1 = (OAuthToken) await OauthTokenProvider.GetAsync(cancellation: cancellationToken).ConfigureAwait(false);
+
+                    tokenBaseLocalVars.Add(oauthTokenLocalVar1);
+
+                    oauthTokenLocalVar1.UseInHeader(httpRequestMessageLocalVar, "");
+
+                    string[] contentTypes = new string[] {
+                        "multipart/form-data"
+                    };
+
+                    string[] acceptLocalVars = new string[] {
+                        "application/json"
+                    };
+
+                    IEnumerable<MediaTypeWithQualityHeaderValue> acceptHeaderValuesLocalVar = ClientUtils.SelectHeaderAcceptArray(acceptLocalVars);
+
+                    foreach (var acceptLocalVar in acceptHeaderValuesLocalVar)
+                        httpRequestMessageLocalVar.Headers.Accept.Add(acceptLocalVar);
+                    httpRequestMessageLocalVar.Method = new HttpMethod("POST");
+
+                    DateTime requestedAtLocalVar = DateTime.UtcNow;
+
+                    using (HttpResponseMessage httpResponseMessageLocalVar = await HttpClient.SendAsync(httpRequestMessageLocalVar, cancellationToken).ConfigureAwait(false))
+                    {
+                        ILogger<UploadFilesApiResponse> apiResponseLoggerLocalVar = LoggerFactory.CreateLogger<UploadFilesApiResponse>();
+                        UploadFilesApiResponse apiResponseLocalVar;
+
+                        switch ((int)httpResponseMessageLocalVar.StatusCode) {
+                            default: {
+                                string responseContentLocalVar = await httpResponseMessageLocalVar.Content.ReadAsStringAsync().ConfigureAwait(false);
+                                apiResponseLocalVar = new UploadFilesApiResponse(apiResponseLoggerLocalVar, httpRequestMessageLocalVar, httpResponseMessageLocalVar, responseContentLocalVar, "/pet/{petId}/uploadImages", requestedAtLocalVar, _jsonSerializerOptions);
+
+                                break;
+                            }
+                        }
+
+                        AfterUploadFilesDefaultImplementation(apiResponseLocalVar, files, petId);
+
+                        Events.ExecuteOnUploadFiles(apiResponseLocalVar);
+
+                        if (apiResponseLocalVar.StatusCode == (HttpStatusCode) 429)
+                            foreach(TokenBase tokenBaseLocalVar in tokenBaseLocalVars)
+                                tokenBaseLocalVar.BeginRateLimit();
+
+                        return apiResponseLocalVar;
+                    }
+                }
+            }
+            catch(Exception e)
+            {
+                OnErrorUploadFilesDefaultImplementation(e, "/pet/{petId}/uploadImages", uriBuilderLocalVar.Path, files, petId);
+                Events.ExecuteOnErrorUploadFiles(e);
+                throw;
+            }
+        }
+
+        /// <summary>
+        /// The <see cref="UploadFilesApiResponse"/>
+        /// </summary>
+        public partial class UploadFilesApiResponse : Org.OpenAPITools.Client.ApiResponse, IUploadFilesApiResponse
+        {
+            /// <summary>
+            /// The logger
+            /// </summary>
+            public ILogger<UploadFilesApiResponse> Logger { get; }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="rawContent"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, string rawContent, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, rawContent, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            /// <summary>
+            /// The <see cref="UploadFilesApiResponse"/>
+            /// </summary>
+            /// <param name="logger"></param>
+            /// <param name="httpRequestMessage"></param>
+            /// <param name="httpResponseMessage"></param>
+            /// <param name="contentStream"></param>
+            /// <param name="path"></param>
+            /// <param name="requestedAt"></param>
+            /// <param name="jsonSerializerOptions"></param>
+            public UploadFilesApiResponse(ILogger<UploadFilesApiResponse> logger, System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage, System.IO.Stream contentStream, string path, DateTime requestedAt, System.Text.Json.JsonSerializerOptions jsonSerializerOptions) : base(httpRequestMessage, httpResponseMessage, contentStream, path, requestedAt, jsonSerializerOptions)
+            {
+                Logger = logger;
+                OnCreated(httpRequestMessage, httpResponseMessage);
+            }
+
+            partial void OnCreated(global::System.Net.Http.HttpRequestMessage httpRequestMessage, System.Net.Http.HttpResponseMessage httpResponseMessage);
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public bool IsOk => 200 == (int)StatusCode;
+
+            /// <summary>
+            /// Deserializes the response if the response is 200 Ok
+            /// </summary>
+            /// <returns></returns>
+            public Org.OpenAPITools.Model.ApiResponse Ok()
+            {
+                // This logic may be modified with the AsModel.mustache template
+                return IsOk
+                    ? System.Text.Json.JsonSerializer.Deserialize<Org.OpenAPITools.Model.ApiResponse>(RawContent, _jsonSerializerOptions)
+                    : default;
+            }
+
+            /// <summary>
+            /// Returns true if the response is 200 Ok and the deserialized response is not null
+            /// </summary>
+            /// <param name="result"></param>
+            /// <returns></returns>
+            public bool TryOk(out Org.OpenAPITools.Model.ApiResponse result)
+            {
+                result = null;
+
+                try
+                {
+                    result = Ok();
+                } catch (Exception e)
+                {
+                    OnDeserializationErrorDefaultImplementation(e, (HttpStatusCode)200);
+                }
+
+                return result != null;
+            }
+
+            private void OnDeserializationErrorDefaultImplementation(Exception exception, HttpStatusCode httpStatusCode)
+            {
+                bool suppressDefaultLog = false;
+                OnDeserializationError(ref suppressDefaultLog, exception, httpStatusCode);
+                if (!suppressDefaultLog)
+                    Logger.LogError(exception, "An error occurred while deserializing the {code} response.", httpStatusCode);
+            }
+
+            partial void OnDeserializationError(ref bool suppressDefaultLog, Exception exception, HttpStatusCode httpStatusCode);
+        }
     }
 }
diff --git a/samples/client/petstore/csharp/generichost/standard2.0/Petstore/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp/generichost/standard2.0/Petstore/src/Org.OpenAPITools/Client/FileParameter.cs
new file mode 100644
index 000000000000..6150dbcf4774
--- /dev/null
+++ b/samples/client/petstore/csharp/generichost/standard2.0/Petstore/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -0,0 +1,40 @@
+// <auto-generated>
+/*
+ * OpenAPI Petstore
+ *
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+namespace Org.OpenAPITools.Client
+{
+    /// <summary>
+    /// Represents a file to be uploaded as part of a multipart/form-data request.
+    /// </summary>
+    public sealed class FileParameter
+    {
+        /// <summary>
+        /// The file content stream.
+        /// </summary>
+        public global::System.IO.Stream Content { get; }
+
+        /// <summary>
+        /// The filename sent in the Content-Disposition header.
+        /// When null the parameter name from the spec is used as a fallback.
+        /// </summary>
+        public string FileName { get; }
+
+        /// <summary>
+        /// Creates a new <see cref="FileParameter"/>.
+        /// </summary>
+        /// <param name="content">The file content stream.</param>
+        /// <param name="fileName">Optional filename for the Content-Disposition header.</param>
+        public FileParameter(global::System.IO.Stream content, string fileName = null)
+        {
+            Content = content;
+            FileName = fileName;
+        }
+    }
+}
diff --git a/samples/client/petstore/csharp/httpclient/net10/Petstore/README.md b/samples/client/petstore/csharp/httpclient/net10/Petstore/README.md
index 73a7b83f20ce..1797a4d9ca09 100644
--- a/samples/client/petstore/csharp/httpclient/net10/Petstore/README.md
+++ b/samples/client/petstore/csharp/httpclient/net10/Petstore/README.md
@@ -178,6 +178,7 @@ Class | Method | HTTP request | Description
 *PetApi* | [**UpdatePetWithForm**](docs/PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data
 *PetApi* | [**UploadFile**](docs/PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image
 *PetApi* | [**UploadFileWithRequiredFile**](docs/PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required)
+*PetApi* | [**UploadFiles**](docs/PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images
 *StoreApi* | [**DeleteOrder**](docs/StoreApi.md#deleteorder) | **DELETE** /store/order/{order_id} | Delete purchase order by ID
 *StoreApi* | [**GetInventory**](docs/StoreApi.md#getinventory) | **GET** /store/inventory | Returns pet inventories by status
 *StoreApi* | [**GetOrderById**](docs/StoreApi.md#getorderbyid) | **GET** /store/order/{order_id} | Find purchase order by ID
diff --git a/samples/client/petstore/csharp/httpclient/net10/Petstore/api/openapi.yaml b/samples/client/petstore/csharp/httpclient/net10/Petstore/api/openapi.yaml
index d8106a5755fc..ca451f3fb832 100644
--- a/samples/client/petstore/csharp/httpclient/net10/Petstore/api/openapi.yaml
+++ b/samples/client/petstore/csharp/httpclient/net10/Petstore/api/openapi.yaml
@@ -331,6 +331,40 @@ paths:
       summary: uploads an image
       tags:
       - pet
+  /pet/{petId}/uploadImages:
+    post:
+      description: ""
+      operationId: uploadFiles
+      parameters:
+      - description: ID of pet to update
+        explode: false
+        in: path
+        name: petId
+        required: true
+        schema:
+          format: int64
+          type: integer
+        style: simple
+      requestBody:
+        content:
+          multipart/form-data:
+            schema:
+              $ref: "#/components/schemas/uploadFiles_request"
+        required: true
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ApiResponse"
+          description: successful operation
+      security:
+      - petstore_auth:
+        - write:pets
+        - read:pets
+      summary: uploads an images
+      tags:
+      - pet
   /store/inventory:
     get:
       description: Returns a map of status codes to quantities
@@ -2924,6 +2958,16 @@ components:
           format: binary
           type: string
       type: object
+    uploadFiles_request:
+      properties:
+        files:
+          items:
+            format: binary
+            type: string
+          type: array
+      required:
+      - files
+      type: object
     testEnumParameters_request:
       properties:
         enum_form_string_array:
diff --git a/samples/client/petstore/csharp/httpclient/net10/Petstore/docs/PetApi.md b/samples/client/petstore/csharp/httpclient/net10/Petstore/docs/PetApi.md
index e8c203c040bd..934a829307a0 100644
--- a/samples/client/petstore/csharp/httpclient/net10/Petstore/docs/PetApi.md
+++ b/samples/client/petstore/csharp/httpclient/net10/Petstore/docs/PetApi.md
@@ -13,6 +13,7 @@ All URIs are relative to *http://petstore.swagger.io:80/v2*
 | [**UpdatePetWithForm**](PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data |
 | [**UploadFile**](PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image |
 | [**UploadFileWithRequiredFile**](PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required) |
+| [**UploadFiles**](PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images |
 
 <a id="addpet"></a>
 # **AddPet**
@@ -896,3 +897,101 @@ catch (ApiException e)
 
 [[Back to top]](#) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to Model list]](../README.md#documentation-for-models) [[Back to README]](../README.md)
 
+<a id="uploadfiles"></a>
+# **UploadFiles**
+> ApiResponse UploadFiles (long petId, List<FileParameter> files)
+
+uploads an images
+
+### Example
+```csharp
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Net.Http;
+using Org.OpenAPITools.Api;
+using Org.OpenAPITools.Client;
+using Org.OpenAPITools.Model;
+
+namespace Example
+{
+    public class UploadFilesExample
+    {
+        public static void Main()
+        {
+            Configuration config = new Configuration();
+            config.BasePath = "http://petstore.swagger.io:80/v2";
+            // Configure OAuth2 access token for authorization: petstore_auth
+            config.AccessToken = "YOUR_ACCESS_TOKEN";
+
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new PetApi(httpClient, config, httpClientHandler);
+            var petId = 789L;  // long | ID of pet to update
+            var files = new List<FileParameter>(); // List<FileParameter> | 
+
+            try
+            {
+                // uploads an images
+                ApiResponse result = apiInstance.UploadFiles(petId, files);
+                Debug.WriteLine(result);
+            }
+            catch (ApiException  e)
+            {
+                Debug.Print("Exception when calling PetApi.UploadFiles: " + e.Message);
+                Debug.Print("Status Code: " + e.ErrorCode);
+                Debug.Print(e.StackTrace);
+            }
+        }
+    }
+}
+```
+
+#### Using the UploadFilesWithHttpInfo variant
+This returns an ApiResponse object which contains the response data, status code and headers.
+
+```csharp
+try
+{
+    // uploads an images
+    ApiResponse<ApiResponse> response = apiInstance.UploadFilesWithHttpInfo(petId, files);
+    Debug.Write("Status Code: " + response.StatusCode);
+    Debug.Write("Response Headers: " + response.Headers);
+    Debug.Write("Response Body: " + response.Data);
+}
+catch (ApiException e)
+{
+    Debug.Print("Exception when calling PetApi.UploadFilesWithHttpInfo: " + e.Message);
+    Debug.Print("Status Code: " + e.ErrorCode);
+    Debug.Print(e.StackTrace);
+}
+```
+
+### Parameters
+
+| Name | Type | Description | Notes |
+|------|------|-------------|-------|
+| **petId** | **long** | ID of pet to update |  |
+| **files** | **List&lt;FileParameter&gt;** |  |  |
+
+### Return type
+
+[**ApiResponse**](ApiResponse.md)
+
+### Authorization
+
+[petstore_auth](../README.md#petstore_auth)
+
+### HTTP request headers
+
+ - **Content-Type**: multipart/form-data
+ - **Accept**: application/json
+
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **200** | successful operation |  -  |
+
+[[Back to top]](#) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to Model list]](../README.md#documentation-for-models) [[Back to README]](../README.md)
+
diff --git a/samples/client/petstore/csharp/httpclient/net10/Petstore/src/Org.OpenAPITools/Api/PetApi.cs b/samples/client/petstore/csharp/httpclient/net10/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
index c76f3f3b7dfe..c84a19eb0d8e 100644
--- a/samples/client/petstore/csharp/httpclient/net10/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
+++ b/samples/client/petstore/csharp/httpclient/net10/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
@@ -214,6 +214,26 @@ public interface IPetApiSync : IApiAccessor
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <returns>ApiResponse of ApiResponse</returns>
         ApiResponse<ApiResponse> UploadFileWithRequiredFileWithHttpInfo(long petId, FileParameter requiredFile, string? additionalMetadata = default);
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <returns>ApiResponse</returns>
+        ApiResponse UploadFiles(long petId, List<FileParameter> files);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <returns>ApiResponse of ApiResponse</returns>
+        ApiResponse<ApiResponse> UploadFilesWithHttpInfo(long petId, List<FileParameter> files);
         #endregion Synchronous Operations
     }
 
@@ -446,6 +466,31 @@ public interface IPetApiAsync : IApiAccessor
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns>Task of ApiResponse (ApiResponse)</returns>
         System.Threading.Tasks.Task<ApiResponse<ApiResponse>> UploadFileWithRequiredFileWithHttpInfoAsync(long petId, FileParameter requiredFile, string? additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns>Task of ApiResponse</returns>
+        System.Threading.Tasks.Task<ApiResponse> UploadFilesAsync(long petId, List<FileParameter> files, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns>Task of ApiResponse (ApiResponse)</returns>
+        System.Threading.Tasks.Task<ApiResponse<ApiResponse>> UploadFilesWithHttpInfoAsync(long petId, List<FileParameter> files, System.Threading.CancellationToken cancellationToken = default);
         #endregion Asynchronous Operations
     }
 
@@ -1994,5 +2039,140 @@ public async System.Threading.Tasks.Task<ApiResponse> UploadFileWithRequiredFile
             return localVarResponse;
         }
 
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <returns>ApiResponse</returns>
+        public ApiResponse UploadFiles(long petId, List<FileParameter> files)
+        {
+            Org.OpenAPITools.Client.ApiResponse<ApiResponse> localVarResponse = UploadFilesWithHttpInfo(petId, files);
+            return localVarResponse.Data;
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <returns>ApiResponse of ApiResponse</returns>
+        public Org.OpenAPITools.Client.ApiResponse<ApiResponse> UploadFilesWithHttpInfo(long petId, List<FileParameter> files)
+        {
+            // verify the required parameter 'files' is set
+            if (files == null)
+                throw new Org.OpenAPITools.Client.ApiException(400, "Missing required parameter 'files' when calling PetApi->UploadFiles");
+
+            Org.OpenAPITools.Client.RequestOptions localVarRequestOptions = new Org.OpenAPITools.Client.RequestOptions();
+
+            string[] _contentTypes = new string[] {
+                "multipart/form-data"
+            };
+
+            // to determine the Accept header
+            string[] _accepts = new string[] {
+                "application/json"
+            };
+
+            var localVarContentType = Org.OpenAPITools.Client.ClientUtils.SelectHeaderContentType(_contentTypes);
+            if (localVarContentType != null) localVarRequestOptions.HeaderParameters.Add("Content-Type", localVarContentType);
+
+            var localVarAccept = Org.OpenAPITools.Client.ClientUtils.SelectHeaderAccept(_accepts);
+            if (localVarAccept != null) localVarRequestOptions.HeaderParameters.Add("Accept", localVarAccept);
+
+            localVarRequestOptions.PathParameters.Add("petId", Org.OpenAPITools.Client.ClientUtils.ParameterToString(petId)); // path parameter
+            localVarRequestOptions.FileParameters.Add("files", files);
+
+            // authentication (petstore_auth) required
+            // oauth required
+            if (!string.IsNullOrEmpty(this.Configuration.AccessToken) && !localVarRequestOptions.HeaderParameters.ContainsKey("Authorization"))
+            {
+                localVarRequestOptions.HeaderParameters.Add("Authorization", "Bearer " + this.Configuration.AccessToken);
+            }
+
+            // make the HTTP request
+            var localVarResponse = this.Client.Post<ApiResponse>("/pet/{petId}/uploadImages", localVarRequestOptions, this.Configuration);
+
+            if (this.ExceptionFactory != null)
+            {
+                Exception _exception = this.ExceptionFactory("UploadFiles", localVarResponse);
+                if (_exception != null) throw _exception;
+            }
+
+            return localVarResponse;
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns>Task of ApiResponse</returns>
+        public async System.Threading.Tasks.Task<ApiResponse> UploadFilesAsync(long petId, List<FileParameter> files, System.Threading.CancellationToken cancellationToken = default)
+        {
+            Org.OpenAPITools.Client.ApiResponse<ApiResponse> localVarResponse = await UploadFilesWithHttpInfoAsync(petId, files, cancellationToken).ConfigureAwait(false);
+            return localVarResponse.Data;
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns>Task of ApiResponse (ApiResponse)</returns>
+        public async System.Threading.Tasks.Task<Org.OpenAPITools.Client.ApiResponse<ApiResponse>> UploadFilesWithHttpInfoAsync(long petId, List<FileParameter> files, System.Threading.CancellationToken cancellationToken = default)
+        {
+            // verify the required parameter 'files' is set
+            if (files == null)
+                throw new Org.OpenAPITools.Client.ApiException(400, "Missing required parameter 'files' when calling PetApi->UploadFiles");
+
+
+            Org.OpenAPITools.Client.RequestOptions localVarRequestOptions = new Org.OpenAPITools.Client.RequestOptions();
+
+            string[] _contentTypes = new string[] {
+                "multipart/form-data"
+            };
+
+            // to determine the Accept header
+            string[] _accepts = new string[] {
+                "application/json"
+            };
+
+
+            var localVarContentType = Org.OpenAPITools.Client.ClientUtils.SelectHeaderContentType(_contentTypes);
+            if (localVarContentType != null) localVarRequestOptions.HeaderParameters.Add("Content-Type", localVarContentType);
+
+            var localVarAccept = Org.OpenAPITools.Client.ClientUtils.SelectHeaderAccept(_accepts);
+            if (localVarAccept != null) localVarRequestOptions.HeaderParameters.Add("Accept", localVarAccept);
+
+            localVarRequestOptions.PathParameters.Add("petId", Org.OpenAPITools.Client.ClientUtils.ParameterToString(petId)); // path parameter
+            localVarRequestOptions.FileParameters.Add("files", files);
+
+            // authentication (petstore_auth) required
+            // oauth required
+            if (!string.IsNullOrEmpty(this.Configuration.AccessToken) && !localVarRequestOptions.HeaderParameters.ContainsKey("Authorization"))
+            {
+                localVarRequestOptions.HeaderParameters.Add("Authorization", "Bearer " + this.Configuration.AccessToken);
+            }
+
+            // make the HTTP request
+
+            var localVarResponse = await this.AsynchronousClient.PostAsync<ApiResponse>("/pet/{petId}/uploadImages", localVarRequestOptions, this.Configuration, cancellationToken).ConfigureAwait(false);
+
+            if (this.ExceptionFactory != null)
+            {
+                Exception _exception = this.ExceptionFactory("UploadFiles", localVarResponse);
+                if (_exception != null) throw _exception;
+            }
+
+            return localVarResponse;
+        }
+
     }
 }
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/README.md b/samples/client/petstore/csharp/httpclient/net9/Petstore/README.md
index 73a7b83f20ce..1797a4d9ca09 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/README.md
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/README.md
@@ -178,6 +178,7 @@ Class | Method | HTTP request | Description
 *PetApi* | [**UpdatePetWithForm**](docs/PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data
 *PetApi* | [**UploadFile**](docs/PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image
 *PetApi* | [**UploadFileWithRequiredFile**](docs/PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required)
+*PetApi* | [**UploadFiles**](docs/PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images
 *StoreApi* | [**DeleteOrder**](docs/StoreApi.md#deleteorder) | **DELETE** /store/order/{order_id} | Delete purchase order by ID
 *StoreApi* | [**GetInventory**](docs/StoreApi.md#getinventory) | **GET** /store/inventory | Returns pet inventories by status
 *StoreApi* | [**GetOrderById**](docs/StoreApi.md#getorderbyid) | **GET** /store/order/{order_id} | Find purchase order by ID
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/api/openapi.yaml b/samples/client/petstore/csharp/httpclient/net9/Petstore/api/openapi.yaml
index d8106a5755fc..ca451f3fb832 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/api/openapi.yaml
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/api/openapi.yaml
@@ -331,6 +331,40 @@ paths:
       summary: uploads an image
       tags:
       - pet
+  /pet/{petId}/uploadImages:
+    post:
+      description: ""
+      operationId: uploadFiles
+      parameters:
+      - description: ID of pet to update
+        explode: false
+        in: path
+        name: petId
+        required: true
+        schema:
+          format: int64
+          type: integer
+        style: simple
+      requestBody:
+        content:
+          multipart/form-data:
+            schema:
+              $ref: "#/components/schemas/uploadFiles_request"
+        required: true
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ApiResponse"
+          description: successful operation
+      security:
+      - petstore_auth:
+        - write:pets
+        - read:pets
+      summary: uploads an images
+      tags:
+      - pet
   /store/inventory:
     get:
       description: Returns a map of status codes to quantities
@@ -2924,6 +2958,16 @@ components:
           format: binary
           type: string
       type: object
+    uploadFiles_request:
+      properties:
+        files:
+          items:
+            format: binary
+            type: string
+          type: array
+      required:
+      - files
+      type: object
     testEnumParameters_request:
       properties:
         enum_form_string_array:
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/docs/PetApi.md b/samples/client/petstore/csharp/httpclient/net9/Petstore/docs/PetApi.md
index e8c203c040bd..934a829307a0 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/docs/PetApi.md
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/docs/PetApi.md
@@ -13,6 +13,7 @@ All URIs are relative to *http://petstore.swagger.io:80/v2*
 | [**UpdatePetWithForm**](PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data |
 | [**UploadFile**](PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image |
 | [**UploadFileWithRequiredFile**](PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required) |
+| [**UploadFiles**](PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images |
 
 <a id="addpet"></a>
 # **AddPet**
@@ -896,3 +897,101 @@ catch (ApiException e)
 
 [[Back to top]](#) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to Model list]](../README.md#documentation-for-models) [[Back to README]](../README.md)
 
+<a id="uploadfiles"></a>
+# **UploadFiles**
+> ApiResponse UploadFiles (long petId, List<FileParameter> files)
+
+uploads an images
+
+### Example
+```csharp
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Net.Http;
+using Org.OpenAPITools.Api;
+using Org.OpenAPITools.Client;
+using Org.OpenAPITools.Model;
+
+namespace Example
+{
+    public class UploadFilesExample
+    {
+        public static void Main()
+        {
+            Configuration config = new Configuration();
+            config.BasePath = "http://petstore.swagger.io:80/v2";
+            // Configure OAuth2 access token for authorization: petstore_auth
+            config.AccessToken = "YOUR_ACCESS_TOKEN";
+
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new PetApi(httpClient, config, httpClientHandler);
+            var petId = 789L;  // long | ID of pet to update
+            var files = new List<FileParameter>(); // List<FileParameter> | 
+
+            try
+            {
+                // uploads an images
+                ApiResponse result = apiInstance.UploadFiles(petId, files);
+                Debug.WriteLine(result);
+            }
+            catch (ApiException  e)
+            {
+                Debug.Print("Exception when calling PetApi.UploadFiles: " + e.Message);
+                Debug.Print("Status Code: " + e.ErrorCode);
+                Debug.Print(e.StackTrace);
+            }
+        }
+    }
+}
+```
+
+#### Using the UploadFilesWithHttpInfo variant
+This returns an ApiResponse object which contains the response data, status code and headers.
+
+```csharp
+try
+{
+    // uploads an images
+    ApiResponse<ApiResponse> response = apiInstance.UploadFilesWithHttpInfo(petId, files);
+    Debug.Write("Status Code: " + response.StatusCode);
+    Debug.Write("Response Headers: " + response.Headers);
+    Debug.Write("Response Body: " + response.Data);
+}
+catch (ApiException e)
+{
+    Debug.Print("Exception when calling PetApi.UploadFilesWithHttpInfo: " + e.Message);
+    Debug.Print("Status Code: " + e.ErrorCode);
+    Debug.Print(e.StackTrace);
+}
+```
+
+### Parameters
+
+| Name | Type | Description | Notes |
+|------|------|-------------|-------|
+| **petId** | **long** | ID of pet to update |  |
+| **files** | **List&lt;FileParameter&gt;** |  |  |
+
+### Return type
+
+[**ApiResponse**](ApiResponse.md)
+
+### Authorization
+
+[petstore_auth](../README.md#petstore_auth)
+
+### HTTP request headers
+
+ - **Content-Type**: multipart/form-data
+ - **Accept**: application/json
+
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **200** | successful operation |  -  |
+
+[[Back to top]](#) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to Model list]](../README.md#documentation-for-models) [[Back to README]](../README.md)
+
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Api/PetApi.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
index c76f3f3b7dfe..c84a19eb0d8e 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
@@ -214,6 +214,26 @@ public interface IPetApiSync : IApiAccessor
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <returns>ApiResponse of ApiResponse</returns>
         ApiResponse<ApiResponse> UploadFileWithRequiredFileWithHttpInfo(long petId, FileParameter requiredFile, string? additionalMetadata = default);
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <returns>ApiResponse</returns>
+        ApiResponse UploadFiles(long petId, List<FileParameter> files);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <returns>ApiResponse of ApiResponse</returns>
+        ApiResponse<ApiResponse> UploadFilesWithHttpInfo(long petId, List<FileParameter> files);
         #endregion Synchronous Operations
     }
 
@@ -446,6 +466,31 @@ public interface IPetApiAsync : IApiAccessor
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns>Task of ApiResponse (ApiResponse)</returns>
         System.Threading.Tasks.Task<ApiResponse<ApiResponse>> UploadFileWithRequiredFileWithHttpInfoAsync(long petId, FileParameter requiredFile, string? additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns>Task of ApiResponse</returns>
+        System.Threading.Tasks.Task<ApiResponse> UploadFilesAsync(long petId, List<FileParameter> files, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns>Task of ApiResponse (ApiResponse)</returns>
+        System.Threading.Tasks.Task<ApiResponse<ApiResponse>> UploadFilesWithHttpInfoAsync(long petId, List<FileParameter> files, System.Threading.CancellationToken cancellationToken = default);
         #endregion Asynchronous Operations
     }
 
@@ -1994,5 +2039,140 @@ public async System.Threading.Tasks.Task<ApiResponse> UploadFileWithRequiredFile
             return localVarResponse;
         }
 
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <returns>ApiResponse</returns>
+        public ApiResponse UploadFiles(long petId, List<FileParameter> files)
+        {
+            Org.OpenAPITools.Client.ApiResponse<ApiResponse> localVarResponse = UploadFilesWithHttpInfo(petId, files);
+            return localVarResponse.Data;
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <returns>ApiResponse of ApiResponse</returns>
+        public Org.OpenAPITools.Client.ApiResponse<ApiResponse> UploadFilesWithHttpInfo(long petId, List<FileParameter> files)
+        {
+            // verify the required parameter 'files' is set
+            if (files == null)
+                throw new Org.OpenAPITools.Client.ApiException(400, "Missing required parameter 'files' when calling PetApi->UploadFiles");
+
+            Org.OpenAPITools.Client.RequestOptions localVarRequestOptions = new Org.OpenAPITools.Client.RequestOptions();
+
+            string[] _contentTypes = new string[] {
+                "multipart/form-data"
+            };
+
+            // to determine the Accept header
+            string[] _accepts = new string[] {
+                "application/json"
+            };
+
+            var localVarContentType = Org.OpenAPITools.Client.ClientUtils.SelectHeaderContentType(_contentTypes);
+            if (localVarContentType != null) localVarRequestOptions.HeaderParameters.Add("Content-Type", localVarContentType);
+
+            var localVarAccept = Org.OpenAPITools.Client.ClientUtils.SelectHeaderAccept(_accepts);
+            if (localVarAccept != null) localVarRequestOptions.HeaderParameters.Add("Accept", localVarAccept);
+
+            localVarRequestOptions.PathParameters.Add("petId", Org.OpenAPITools.Client.ClientUtils.ParameterToString(petId)); // path parameter
+            localVarRequestOptions.FileParameters.Add("files", files);
+
+            // authentication (petstore_auth) required
+            // oauth required
+            if (!string.IsNullOrEmpty(this.Configuration.AccessToken) && !localVarRequestOptions.HeaderParameters.ContainsKey("Authorization"))
+            {
+                localVarRequestOptions.HeaderParameters.Add("Authorization", "Bearer " + this.Configuration.AccessToken);
+            }
+
+            // make the HTTP request
+            var localVarResponse = this.Client.Post<ApiResponse>("/pet/{petId}/uploadImages", localVarRequestOptions, this.Configuration);
+
+            if (this.ExceptionFactory != null)
+            {
+                Exception _exception = this.ExceptionFactory("UploadFiles", localVarResponse);
+                if (_exception != null) throw _exception;
+            }
+
+            return localVarResponse;
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns>Task of ApiResponse</returns>
+        public async System.Threading.Tasks.Task<ApiResponse> UploadFilesAsync(long petId, List<FileParameter> files, System.Threading.CancellationToken cancellationToken = default)
+        {
+            Org.OpenAPITools.Client.ApiResponse<ApiResponse> localVarResponse = await UploadFilesWithHttpInfoAsync(petId, files, cancellationToken).ConfigureAwait(false);
+            return localVarResponse.Data;
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns>Task of ApiResponse (ApiResponse)</returns>
+        public async System.Threading.Tasks.Task<Org.OpenAPITools.Client.ApiResponse<ApiResponse>> UploadFilesWithHttpInfoAsync(long petId, List<FileParameter> files, System.Threading.CancellationToken cancellationToken = default)
+        {
+            // verify the required parameter 'files' is set
+            if (files == null)
+                throw new Org.OpenAPITools.Client.ApiException(400, "Missing required parameter 'files' when calling PetApi->UploadFiles");
+
+
+            Org.OpenAPITools.Client.RequestOptions localVarRequestOptions = new Org.OpenAPITools.Client.RequestOptions();
+
+            string[] _contentTypes = new string[] {
+                "multipart/form-data"
+            };
+
+            // to determine the Accept header
+            string[] _accepts = new string[] {
+                "application/json"
+            };
+
+
+            var localVarContentType = Org.OpenAPITools.Client.ClientUtils.SelectHeaderContentType(_contentTypes);
+            if (localVarContentType != null) localVarRequestOptions.HeaderParameters.Add("Content-Type", localVarContentType);
+
+            var localVarAccept = Org.OpenAPITools.Client.ClientUtils.SelectHeaderAccept(_accepts);
+            if (localVarAccept != null) localVarRequestOptions.HeaderParameters.Add("Accept", localVarAccept);
+
+            localVarRequestOptions.PathParameters.Add("petId", Org.OpenAPITools.Client.ClientUtils.ParameterToString(petId)); // path parameter
+            localVarRequestOptions.FileParameters.Add("files", files);
+
+            // authentication (petstore_auth) required
+            // oauth required
+            if (!string.IsNullOrEmpty(this.Configuration.AccessToken) && !localVarRequestOptions.HeaderParameters.ContainsKey("Authorization"))
+            {
+                localVarRequestOptions.HeaderParameters.Add("Authorization", "Bearer " + this.Configuration.AccessToken);
+            }
+
+            // make the HTTP request
+
+            var localVarResponse = await this.AsynchronousClient.PostAsync<ApiResponse>("/pet/{petId}/uploadImages", localVarRequestOptions, this.Configuration, cancellationToken).ConfigureAwait(false);
+
+            if (this.ExceptionFactory != null)
+            {
+                Exception _exception = this.ExceptionFactory("UploadFiles", localVarResponse);
+                if (_exception != null) throw _exception;
+            }
+
+            return localVarResponse;
+        }
+
     }
 }
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/README.md b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/README.md
index 0a0407f2aa98..50e735052990 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/README.md
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/README.md
@@ -166,6 +166,7 @@ Class | Method | HTTP request | Description
 *PetApi* | [**UpdatePetWithForm**](docs/PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data
 *PetApi* | [**UploadFile**](docs/PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image
 *PetApi* | [**UploadFileWithRequiredFile**](docs/PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required)
+*PetApi* | [**UploadFiles**](docs/PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images
 *StoreApi* | [**DeleteOrder**](docs/StoreApi.md#deleteorder) | **DELETE** /store/order/{order_id} | Delete purchase order by ID
 *StoreApi* | [**GetInventory**](docs/StoreApi.md#getinventory) | **GET** /store/inventory | Returns pet inventories by status
 *StoreApi* | [**GetOrderById**](docs/StoreApi.md#getorderbyid) | **GET** /store/order/{order_id} | Find purchase order by ID
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/api/openapi.yaml b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/api/openapi.yaml
index d8106a5755fc..ca451f3fb832 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/api/openapi.yaml
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/api/openapi.yaml
@@ -331,6 +331,40 @@ paths:
       summary: uploads an image
       tags:
       - pet
+  /pet/{petId}/uploadImages:
+    post:
+      description: ""
+      operationId: uploadFiles
+      parameters:
+      - description: ID of pet to update
+        explode: false
+        in: path
+        name: petId
+        required: true
+        schema:
+          format: int64
+          type: integer
+        style: simple
+      requestBody:
+        content:
+          multipart/form-data:
+            schema:
+              $ref: "#/components/schemas/uploadFiles_request"
+        required: true
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ApiResponse"
+          description: successful operation
+      security:
+      - petstore_auth:
+        - write:pets
+        - read:pets
+      summary: uploads an images
+      tags:
+      - pet
   /store/inventory:
     get:
       description: Returns a map of status codes to quantities
@@ -2924,6 +2958,16 @@ components:
           format: binary
           type: string
       type: object
+    uploadFiles_request:
+      properties:
+        files:
+          items:
+            format: binary
+            type: string
+          type: array
+      required:
+      - files
+      type: object
     testEnumParameters_request:
       properties:
         enum_form_string_array:
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/docs/PetApi.md b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/docs/PetApi.md
index b7d549524b65..eb03434c366b 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/docs/PetApi.md
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/docs/PetApi.md
@@ -13,6 +13,7 @@ All URIs are relative to *http://petstore.swagger.io:80/v2*
 | [**UpdatePetWithForm**](PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data |
 | [**UploadFile**](PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image |
 | [**UploadFileWithRequiredFile**](PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required) |
+| [**UploadFiles**](PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images |
 
 <a id="addpet"></a>
 # **AddPet**
@@ -896,3 +897,101 @@ catch (ApiException e)
 
 [[Back to top]](#) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to Model list]](../README.md#documentation-for-models) [[Back to README]](../README.md)
 
+<a id="uploadfiles"></a>
+# **UploadFiles**
+> ApiResponse UploadFiles (long petId, List<FileParameter> files)
+
+uploads an images
+
+### Example
+```csharp
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Net.Http;
+using Org.OpenAPITools.Api;
+using Org.OpenAPITools.Client;
+using Org.OpenAPITools.Model;
+
+namespace Example
+{
+    public class UploadFilesExample
+    {
+        public static void Main()
+        {
+            Configuration config = new Configuration();
+            config.BasePath = "http://petstore.swagger.io:80/v2";
+            // Configure OAuth2 access token for authorization: petstore_auth
+            config.AccessToken = "YOUR_ACCESS_TOKEN";
+
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new PetApi(httpClient, config, httpClientHandler);
+            var petId = 789L;  // long | ID of pet to update
+            var files = new List<FileParameter>(); // List<FileParameter> | 
+
+            try
+            {
+                // uploads an images
+                ApiResponse result = apiInstance.UploadFiles(petId, files);
+                Debug.WriteLine(result);
+            }
+            catch (ApiException  e)
+            {
+                Debug.Print("Exception when calling PetApi.UploadFiles: " + e.Message);
+                Debug.Print("Status Code: " + e.ErrorCode);
+                Debug.Print(e.StackTrace);
+            }
+        }
+    }
+}
+```
+
+#### Using the UploadFilesWithHttpInfo variant
+This returns an ApiResponse object which contains the response data, status code and headers.
+
+```csharp
+try
+{
+    // uploads an images
+    ApiResponse<ApiResponse> response = apiInstance.UploadFilesWithHttpInfo(petId, files);
+    Debug.Write("Status Code: " + response.StatusCode);
+    Debug.Write("Response Headers: " + response.Headers);
+    Debug.Write("Response Body: " + response.Data);
+}
+catch (ApiException e)
+{
+    Debug.Print("Exception when calling PetApi.UploadFilesWithHttpInfo: " + e.Message);
+    Debug.Print("Status Code: " + e.ErrorCode);
+    Debug.Print(e.StackTrace);
+}
+```
+
+### Parameters
+
+| Name | Type | Description | Notes |
+|------|------|-------------|-------|
+| **petId** | **long** | ID of pet to update |  |
+| **files** | **List&lt;FileParameter&gt;** |  |  |
+
+### Return type
+
+[**ApiResponse**](ApiResponse.md)
+
+### Authorization
+
+[petstore_auth](../README.md#petstore_auth)
+
+### HTTP request headers
+
+ - **Content-Type**: multipart/form-data
+ - **Accept**: application/json
+
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **200** | successful operation |  -  |
+
+[[Back to top]](#) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to Model list]](../README.md#documentation-for-models) [[Back to README]](../README.md)
+
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Api/PetApi.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
index ec2d209ced03..fb1604fe0013 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
@@ -214,6 +214,26 @@ public interface IPetApiSync : IApiAccessor
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <returns>ApiResponse of ApiResponse</returns>
         ApiResponse<ApiResponse> UploadFileWithRequiredFileWithHttpInfo(long petId, FileParameter requiredFile, string additionalMetadata = default);
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <returns>ApiResponse</returns>
+        ApiResponse UploadFiles(long petId, List<FileParameter> files);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <returns>ApiResponse of ApiResponse</returns>
+        ApiResponse<ApiResponse> UploadFilesWithHttpInfo(long petId, List<FileParameter> files);
         #endregion Synchronous Operations
     }
 
@@ -446,6 +466,31 @@ public interface IPetApiAsync : IApiAccessor
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns>Task of ApiResponse (ApiResponse)</returns>
         System.Threading.Tasks.Task<ApiResponse<ApiResponse>> UploadFileWithRequiredFileWithHttpInfoAsync(long petId, FileParameter requiredFile, string additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns>Task of ApiResponse</returns>
+        System.Threading.Tasks.Task<ApiResponse> UploadFilesAsync(long petId, List<FileParameter> files, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns>Task of ApiResponse (ApiResponse)</returns>
+        System.Threading.Tasks.Task<ApiResponse<ApiResponse>> UploadFilesWithHttpInfoAsync(long petId, List<FileParameter> files, System.Threading.CancellationToken cancellationToken = default);
         #endregion Asynchronous Operations
     }
 
@@ -1994,5 +2039,140 @@ public async System.Threading.Tasks.Task<ApiResponse> UploadFileWithRequiredFile
             return localVarResponse;
         }
 
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <returns>ApiResponse</returns>
+        public ApiResponse UploadFiles(long petId, List<FileParameter> files)
+        {
+            Org.OpenAPITools.Client.ApiResponse<ApiResponse> localVarResponse = UploadFilesWithHttpInfo(petId, files);
+            return localVarResponse.Data;
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <returns>ApiResponse of ApiResponse</returns>
+        public Org.OpenAPITools.Client.ApiResponse<ApiResponse> UploadFilesWithHttpInfo(long petId, List<FileParameter> files)
+        {
+            // verify the required parameter 'files' is set
+            if (files == null)
+                throw new Org.OpenAPITools.Client.ApiException(400, "Missing required parameter 'files' when calling PetApi->UploadFiles");
+
+            Org.OpenAPITools.Client.RequestOptions localVarRequestOptions = new Org.OpenAPITools.Client.RequestOptions();
+
+            string[] _contentTypes = new string[] {
+                "multipart/form-data"
+            };
+
+            // to determine the Accept header
+            string[] _accepts = new string[] {
+                "application/json"
+            };
+
+            var localVarContentType = Org.OpenAPITools.Client.ClientUtils.SelectHeaderContentType(_contentTypes);
+            if (localVarContentType != null) localVarRequestOptions.HeaderParameters.Add("Content-Type", localVarContentType);
+
+            var localVarAccept = Org.OpenAPITools.Client.ClientUtils.SelectHeaderAccept(_accepts);
+            if (localVarAccept != null) localVarRequestOptions.HeaderParameters.Add("Accept", localVarAccept);
+
+            localVarRequestOptions.PathParameters.Add("petId", Org.OpenAPITools.Client.ClientUtils.ParameterToString(petId)); // path parameter
+            localVarRequestOptions.FileParameters.Add("files", files);
+
+            // authentication (petstore_auth) required
+            // oauth required
+            if (!string.IsNullOrEmpty(this.Configuration.AccessToken) && !localVarRequestOptions.HeaderParameters.ContainsKey("Authorization"))
+            {
+                localVarRequestOptions.HeaderParameters.Add("Authorization", "Bearer " + this.Configuration.AccessToken);
+            }
+
+            // make the HTTP request
+            var localVarResponse = this.Client.Post<ApiResponse>("/pet/{petId}/uploadImages", localVarRequestOptions, this.Configuration);
+
+            if (this.ExceptionFactory != null)
+            {
+                Exception _exception = this.ExceptionFactory("UploadFiles", localVarResponse);
+                if (_exception != null) throw _exception;
+            }
+
+            return localVarResponse;
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns>Task of ApiResponse</returns>
+        public async System.Threading.Tasks.Task<ApiResponse> UploadFilesAsync(long petId, List<FileParameter> files, System.Threading.CancellationToken cancellationToken = default)
+        {
+            Org.OpenAPITools.Client.ApiResponse<ApiResponse> localVarResponse = await UploadFilesWithHttpInfoAsync(petId, files, cancellationToken).ConfigureAwait(false);
+            return localVarResponse.Data;
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns>Task of ApiResponse (ApiResponse)</returns>
+        public async System.Threading.Tasks.Task<Org.OpenAPITools.Client.ApiResponse<ApiResponse>> UploadFilesWithHttpInfoAsync(long petId, List<FileParameter> files, System.Threading.CancellationToken cancellationToken = default)
+        {
+            // verify the required parameter 'files' is set
+            if (files == null)
+                throw new Org.OpenAPITools.Client.ApiException(400, "Missing required parameter 'files' when calling PetApi->UploadFiles");
+
+
+            Org.OpenAPITools.Client.RequestOptions localVarRequestOptions = new Org.OpenAPITools.Client.RequestOptions();
+
+            string[] _contentTypes = new string[] {
+                "multipart/form-data"
+            };
+
+            // to determine the Accept header
+            string[] _accepts = new string[] {
+                "application/json"
+            };
+
+
+            var localVarContentType = Org.OpenAPITools.Client.ClientUtils.SelectHeaderContentType(_contentTypes);
+            if (localVarContentType != null) localVarRequestOptions.HeaderParameters.Add("Content-Type", localVarContentType);
+
+            var localVarAccept = Org.OpenAPITools.Client.ClientUtils.SelectHeaderAccept(_accepts);
+            if (localVarAccept != null) localVarRequestOptions.HeaderParameters.Add("Accept", localVarAccept);
+
+            localVarRequestOptions.PathParameters.Add("petId", Org.OpenAPITools.Client.ClientUtils.ParameterToString(petId)); // path parameter
+            localVarRequestOptions.FileParameters.Add("files", files);
+
+            // authentication (petstore_auth) required
+            // oauth required
+            if (!string.IsNullOrEmpty(this.Configuration.AccessToken) && !localVarRequestOptions.HeaderParameters.ContainsKey("Authorization"))
+            {
+                localVarRequestOptions.HeaderParameters.Add("Authorization", "Bearer " + this.Configuration.AccessToken);
+            }
+
+            // make the HTTP request
+
+            var localVarResponse = await this.AsynchronousClient.PostAsync<ApiResponse>("/pet/{petId}/uploadImages", localVarRequestOptions, this.Configuration, cancellationToken).ConfigureAwait(false);
+
+            if (this.ExceptionFactory != null)
+            {
+                Exception _exception = this.ExceptionFactory("UploadFiles", localVarResponse);
+                if (_exception != null) throw _exception;
+            }
+
+            return localVarResponse;
+        }
+
     }
 }
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/README.md b/samples/client/petstore/csharp/restsharp/net8/Petstore/README.md
index 1db3095f8f3b..ded19553c295 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/README.md
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/README.md
@@ -153,6 +153,7 @@ Class | Method | HTTP request | Description
 *PetApi* | [**UpdatePetWithForm**](docs/PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data
 *PetApi* | [**UploadFile**](docs/PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image
 *PetApi* | [**UploadFileWithRequiredFile**](docs/PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required)
+*PetApi* | [**UploadFiles**](docs/PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images
 *StoreApi* | [**DeleteOrder**](docs/StoreApi.md#deleteorder) | **DELETE** /store/order/{order_id} | Delete purchase order by ID
 *StoreApi* | [**GetInventory**](docs/StoreApi.md#getinventory) | **GET** /store/inventory | Returns pet inventories by status
 *StoreApi* | [**GetOrderById**](docs/StoreApi.md#getorderbyid) | **GET** /store/order/{order_id} | Find purchase order by ID
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/api/openapi.yaml b/samples/client/petstore/csharp/restsharp/net8/Petstore/api/openapi.yaml
index d8106a5755fc..ca451f3fb832 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/api/openapi.yaml
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/api/openapi.yaml
@@ -331,6 +331,40 @@ paths:
       summary: uploads an image
       tags:
       - pet
+  /pet/{petId}/uploadImages:
+    post:
+      description: ""
+      operationId: uploadFiles
+      parameters:
+      - description: ID of pet to update
+        explode: false
+        in: path
+        name: petId
+        required: true
+        schema:
+          format: int64
+          type: integer
+        style: simple
+      requestBody:
+        content:
+          multipart/form-data:
+            schema:
+              $ref: "#/components/schemas/uploadFiles_request"
+        required: true
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ApiResponse"
+          description: successful operation
+      security:
+      - petstore_auth:
+        - write:pets
+        - read:pets
+      summary: uploads an images
+      tags:
+      - pet
   /store/inventory:
     get:
       description: Returns a map of status codes to quantities
@@ -2924,6 +2958,16 @@ components:
           format: binary
           type: string
       type: object
+    uploadFiles_request:
+      properties:
+        files:
+          items:
+            format: binary
+            type: string
+          type: array
+      required:
+      - files
+      type: object
     testEnumParameters_request:
       properties:
         enum_form_string_array:
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/docs/PetApi.md b/samples/client/petstore/csharp/restsharp/net8/Petstore/docs/PetApi.md
index 5272a0b102c3..829ca6d25184 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/docs/PetApi.md
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/docs/PetApi.md
@@ -13,6 +13,7 @@ All URIs are relative to *http://petstore.swagger.io:80/v2*
 | [**UpdatePetWithForm**](PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data |
 | [**UploadFile**](PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image |
 | [**UploadFileWithRequiredFile**](PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required) |
+| [**UploadFiles**](PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images |
 
 <a id="addpet"></a>
 # **AddPet**
@@ -860,3 +861,97 @@ catch (ApiException e)
 
 [[Back to top]](#) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to Model list]](../README.md#documentation-for-models) [[Back to README]](../README.md)
 
+<a id="uploadfiles"></a>
+# **UploadFiles**
+> ApiResponse UploadFiles (long petId, List<System.IO.Stream> files)
+
+uploads an images
+
+### Example
+```csharp
+using System.Collections.Generic;
+using System.Diagnostics;
+using Org.OpenAPITools.Api;
+using Org.OpenAPITools.Client;
+using Org.OpenAPITools.Model;
+
+namespace Example
+{
+    public class UploadFilesExample
+    {
+        public static void Main()
+        {
+            Configuration config = new Configuration();
+            config.BasePath = "http://petstore.swagger.io:80/v2";
+            // Configure OAuth2 access token for authorization: petstore_auth
+            config.AccessToken = "YOUR_ACCESS_TOKEN";
+
+            var apiInstance = new PetApi(config);
+            var petId = 789L;  // long | ID of pet to update
+            var files = new List<System.IO.Stream>(); // List<System.IO.Stream> | 
+
+            try
+            {
+                // uploads an images
+                ApiResponse result = apiInstance.UploadFiles(petId, files);
+                Debug.WriteLine(result);
+            }
+            catch (ApiException  e)
+            {
+                Debug.Print("Exception when calling PetApi.UploadFiles: " + e.Message);
+                Debug.Print("Status Code: " + e.ErrorCode);
+                Debug.Print(e.StackTrace);
+            }
+        }
+    }
+}
+```
+
+#### Using the UploadFilesWithHttpInfo variant
+This returns an ApiResponse object which contains the response data, status code and headers.
+
+```csharp
+try
+{
+    // uploads an images
+    ApiResponse<ApiResponse> response = apiInstance.UploadFilesWithHttpInfo(petId, files);
+    Debug.Write("Status Code: " + response.StatusCode);
+    Debug.Write("Response Headers: " + response.Headers);
+    Debug.Write("Response Body: " + response.Data);
+}
+catch (ApiException e)
+{
+    Debug.Print("Exception when calling PetApi.UploadFilesWithHttpInfo: " + e.Message);
+    Debug.Print("Status Code: " + e.ErrorCode);
+    Debug.Print(e.StackTrace);
+}
+```
+
+### Parameters
+
+| Name | Type | Description | Notes |
+|------|------|-------------|-------|
+| **petId** | **long** | ID of pet to update |  |
+| **files** | **List&lt;System.IO.Stream&gt;** |  |  |
+
+### Return type
+
+[**ApiResponse**](ApiResponse.md)
+
+### Authorization
+
+[petstore_auth](../README.md#petstore_auth)
+
+### HTTP request headers
+
+ - **Content-Type**: multipart/form-data
+ - **Accept**: application/json
+
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **200** | successful operation |  -  |
+
+[[Back to top]](#) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to Model list]](../README.md#documentation-for-models) [[Back to README]](../README.md)
+
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Api/PetApi.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
index 86b40ec17eb1..1ea79a1c545a 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
@@ -232,6 +232,28 @@ public interface IPetApiSync : IApiAccessor
         /// <param name="operationIndex">Index associated with the operation.</param>
         /// <returns>ApiResponse of ApiResponse</returns>
         ApiResponse<ApiResponse> UploadFileWithRequiredFileWithHttpInfo(long petId, System.IO.Stream requiredFile, string? additionalMetadata = default, int operationIndex = 0);
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="operationIndex">Index associated with the operation.</param>
+        /// <returns>ApiResponse</returns>
+        ApiResponse UploadFiles(long petId, List<System.IO.Stream> files, int operationIndex = 0);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="operationIndex">Index associated with the operation.</param>
+        /// <returns>ApiResponse of ApiResponse</returns>
+        ApiResponse<ApiResponse> UploadFilesWithHttpInfo(long petId, List<System.IO.Stream> files, int operationIndex = 0);
         #endregion Synchronous Operations
     }
 
@@ -482,6 +504,33 @@ public interface IPetApiAsync : IApiAccessor
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns>Task of ApiResponse (ApiResponse)</returns>
         System.Threading.Tasks.Task<ApiResponse<ApiResponse>> UploadFileWithRequiredFileWithHttpInfoAsync(long petId, System.IO.Stream requiredFile, string? additionalMetadata = default, int operationIndex = 0, System.Threading.CancellationToken cancellationToken = default);
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="operationIndex">Index associated with the operation.</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns>Task of ApiResponse</returns>
+        System.Threading.Tasks.Task<ApiResponse> UploadFilesAsync(long petId, List<System.IO.Stream> files, int operationIndex = 0, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="operationIndex">Index associated with the operation.</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns>Task of ApiResponse (ApiResponse)</returns>
+        System.Threading.Tasks.Task<ApiResponse<ApiResponse>> UploadFilesWithHttpInfoAsync(long petId, List<System.IO.Stream> files, int operationIndex = 0, System.Threading.CancellationToken cancellationToken = default);
         #endregion Asynchronous Operations
     }
 
@@ -2351,5 +2400,196 @@ public async System.Threading.Tasks.Task<ApiResponse> UploadFileWithRequiredFile
             return localVarResponse;
         }
 
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="operationIndex">Index associated with the operation.</param>
+        /// <returns>ApiResponse</returns>
+        public ApiResponse UploadFiles(long petId, List<System.IO.Stream> files, int operationIndex = 0)
+        {
+            Org.OpenAPITools.Client.ApiResponse<ApiResponse> localVarResponse = UploadFilesWithHttpInfo(petId, files);
+            return localVarResponse.Data;
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="operationIndex">Index associated with the operation.</param>
+        /// <returns>ApiResponse of ApiResponse</returns>
+        public Org.OpenAPITools.Client.ApiResponse<ApiResponse> UploadFilesWithHttpInfo(long petId, List<System.IO.Stream> files, int operationIndex = 0)
+        {
+            // verify the required parameter 'files' is set
+            if (files == null)
+            {
+                throw new Org.OpenAPITools.Client.ApiException(400, "Missing required parameter 'files' when calling PetApi->UploadFiles");
+            }
+
+            Org.OpenAPITools.Client.RequestOptions localVarRequestOptions = new Org.OpenAPITools.Client.RequestOptions();
+
+            string[] _contentTypes = new string[] {
+                "multipart/form-data"
+            };
+
+            // to determine the Accept header
+            string[] _accepts = new string[] {
+                "application/json"
+            };
+
+            var localVarContentType = Org.OpenAPITools.Client.ClientUtils.SelectHeaderContentType(_contentTypes);
+            var localVarMultipartFormData = localVarContentType == "multipart/form-data";
+            if (localVarContentType != null)
+            {
+                localVarRequestOptions.HeaderParameters.Add("Content-Type", localVarContentType);
+            }
+
+            var localVarAccept = Org.OpenAPITools.Client.ClientUtils.SelectHeaderAccept(_accepts);
+            if (localVarAccept != null)
+            {
+                localVarRequestOptions.HeaderParameters.Add("Accept", localVarAccept);
+            }
+
+            localVarRequestOptions.PathParameters.Add("petId", Org.OpenAPITools.Client.ClientUtils.ParameterToString(petId)); // path parameter
+            foreach (var file in files)
+            {
+                localVarRequestOptions.FileParameters.Add("files", file);
+            }
+
+            localVarRequestOptions.Operation = "PetApi.UploadFiles";
+            localVarRequestOptions.OperationIndex = operationIndex;
+
+            // authentication (petstore_auth) required
+            // oauth required
+            if (!localVarRequestOptions.HeaderParameters.ContainsKey("Authorization"))
+            {
+                if (!string.IsNullOrEmpty(this.Configuration.AccessToken))
+                {
+                    localVarRequestOptions.HeaderParameters.Add("Authorization", "Bearer " + this.Configuration.AccessToken);
+                }
+                else if (!string.IsNullOrEmpty(this.Configuration.OAuthTokenUrl) &&
+                         !string.IsNullOrEmpty(this.Configuration.OAuthClientId) &&
+                         !string.IsNullOrEmpty(this.Configuration.OAuthClientSecret) &&
+                         this.Configuration.OAuthFlow != null)
+                {
+                    localVarRequestOptions.OAuth = true;
+                }
+            }
+
+            // make the HTTP request
+            var localVarResponse = this.Client.Post<ApiResponse>("/pet/{petId}/uploadImages", localVarRequestOptions, this.Configuration);
+            if (this.ExceptionFactory != null)
+            {
+                Exception _exception = this.ExceptionFactory("UploadFiles", localVarResponse);
+                if (_exception != null)
+                {
+                    throw _exception;
+                }
+            }
+
+            return localVarResponse;
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="operationIndex">Index associated with the operation.</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns>Task of ApiResponse</returns>
+        public async System.Threading.Tasks.Task<ApiResponse> UploadFilesAsync(long petId, List<System.IO.Stream> files, int operationIndex = 0, System.Threading.CancellationToken cancellationToken = default)
+        {
+            Org.OpenAPITools.Client.ApiResponse<ApiResponse> localVarResponse = await UploadFilesWithHttpInfoAsync(petId, files, operationIndex, cancellationToken).ConfigureAwait(false);
+            return localVarResponse.Data;
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="operationIndex">Index associated with the operation.</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns>Task of ApiResponse (ApiResponse)</returns>
+        public async System.Threading.Tasks.Task<Org.OpenAPITools.Client.ApiResponse<ApiResponse>> UploadFilesWithHttpInfoAsync(long petId, List<System.IO.Stream> files, int operationIndex = 0, System.Threading.CancellationToken cancellationToken = default)
+        {
+            // verify the required parameter 'files' is set
+            if (files == null)
+            {
+                throw new Org.OpenAPITools.Client.ApiException(400, "Missing required parameter 'files' when calling PetApi->UploadFiles");
+            }
+
+
+            Org.OpenAPITools.Client.RequestOptions localVarRequestOptions = new Org.OpenAPITools.Client.RequestOptions();
+
+            string[] _contentTypes = new string[] {
+                "multipart/form-data"
+            };
+
+            // to determine the Accept header
+            string[] _accepts = new string[] {
+                "application/json"
+            };
+
+            var localVarContentType = Org.OpenAPITools.Client.ClientUtils.SelectHeaderContentType(_contentTypes);
+            if (localVarContentType != null)
+            {
+                localVarRequestOptions.HeaderParameters.Add("Content-Type", localVarContentType);
+            }
+
+            var localVarAccept = Org.OpenAPITools.Client.ClientUtils.SelectHeaderAccept(_accepts);
+            if (localVarAccept != null)
+            {
+                localVarRequestOptions.HeaderParameters.Add("Accept", localVarAccept);
+            }
+
+            localVarRequestOptions.PathParameters.Add("petId", Org.OpenAPITools.Client.ClientUtils.ParameterToString(petId)); // path parameter
+            foreach (var file in files)
+            {
+                localVarRequestOptions.FileParameters.Add("files", file);
+            }
+
+            localVarRequestOptions.Operation = "PetApi.UploadFiles";
+            localVarRequestOptions.OperationIndex = operationIndex;
+
+            // authentication (petstore_auth) required
+            // oauth required
+            if (!localVarRequestOptions.HeaderParameters.ContainsKey("Authorization"))
+            {
+                if (!string.IsNullOrEmpty(this.Configuration.AccessToken))
+                {
+                    localVarRequestOptions.HeaderParameters.Add("Authorization", "Bearer " + this.Configuration.AccessToken);
+                }
+                else if (!string.IsNullOrEmpty(this.Configuration.OAuthTokenUrl) &&
+                         !string.IsNullOrEmpty(this.Configuration.OAuthClientId) &&
+                         !string.IsNullOrEmpty(this.Configuration.OAuthClientSecret) &&
+                         this.Configuration.OAuthFlow != null)
+                {
+                    localVarRequestOptions.OAuth = true;
+                }
+            }
+
+            // make the HTTP request
+            var localVarResponse = await this.AsynchronousClient.PostAsync<ApiResponse>("/pet/{petId}/uploadImages", localVarRequestOptions, this.Configuration, cancellationToken).ConfigureAwait(false);
+
+            if (this.ExceptionFactory != null)
+            {
+                Exception _exception = this.ExceptionFactory("UploadFiles", localVarResponse);
+                if (_exception != null)
+                {
+                    throw _exception;
+                }
+            }
+
+            return localVarResponse;
+        }
+
     }
 }
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/README.md b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/README.md
index f7f95f4a3abf..af9ad0d78405 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/README.md
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/README.md
@@ -141,6 +141,7 @@ Class | Method | HTTP request | Description
 *PetApi* | [**UpdatePetWithForm**](docs/PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data
 *PetApi* | [**UploadFile**](docs/PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image
 *PetApi* | [**UploadFileWithRequiredFile**](docs/PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required)
+*PetApi* | [**UploadFiles**](docs/PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images
 *StoreApi* | [**DeleteOrder**](docs/StoreApi.md#deleteorder) | **DELETE** /store/order/{order_id} | Delete purchase order by ID
 *StoreApi* | [**GetInventory**](docs/StoreApi.md#getinventory) | **GET** /store/inventory | Returns pet inventories by status
 *StoreApi* | [**GetOrderById**](docs/StoreApi.md#getorderbyid) | **GET** /store/order/{order_id} | Find purchase order by ID
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/api/openapi.yaml b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/api/openapi.yaml
index d8106a5755fc..ca451f3fb832 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/api/openapi.yaml
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/api/openapi.yaml
@@ -331,6 +331,40 @@ paths:
       summary: uploads an image
       tags:
       - pet
+  /pet/{petId}/uploadImages:
+    post:
+      description: ""
+      operationId: uploadFiles
+      parameters:
+      - description: ID of pet to update
+        explode: false
+        in: path
+        name: petId
+        required: true
+        schema:
+          format: int64
+          type: integer
+        style: simple
+      requestBody:
+        content:
+          multipart/form-data:
+            schema:
+              $ref: "#/components/schemas/uploadFiles_request"
+        required: true
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ApiResponse"
+          description: successful operation
+      security:
+      - petstore_auth:
+        - write:pets
+        - read:pets
+      summary: uploads an images
+      tags:
+      - pet
   /store/inventory:
     get:
       description: Returns a map of status codes to quantities
@@ -2924,6 +2958,16 @@ components:
           format: binary
           type: string
       type: object
+    uploadFiles_request:
+      properties:
+        files:
+          items:
+            format: binary
+            type: string
+          type: array
+      required:
+      - files
+      type: object
     testEnumParameters_request:
       properties:
         enum_form_string_array:
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/docs/PetApi.md b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/docs/PetApi.md
index 3db7da1cd2fa..cb3a65d239b4 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/docs/PetApi.md
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/docs/PetApi.md
@@ -13,6 +13,7 @@ All URIs are relative to *http://petstore.swagger.io:80/v2*
 | [**UpdatePetWithForm**](PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data |
 | [**UploadFile**](PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image |
 | [**UploadFileWithRequiredFile**](PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required) |
+| [**UploadFiles**](PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images |
 
 <a id="addpet"></a>
 # **AddPet**
@@ -860,3 +861,97 @@ catch (ApiException e)
 
 [[Back to top]](#) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to Model list]](../README.md#documentation-for-models) [[Back to README]](../README.md)
 
+<a id="uploadfiles"></a>
+# **UploadFiles**
+> ApiResponse UploadFiles (long petId, List<System.IO.Stream> files)
+
+uploads an images
+
+### Example
+```csharp
+using System.Collections.Generic;
+using System.Diagnostics;
+using Org.OpenAPITools.Api;
+using Org.OpenAPITools.Client;
+using Org.OpenAPITools.Model;
+
+namespace Example
+{
+    public class UploadFilesExample
+    {
+        public static void Main()
+        {
+            Configuration config = new Configuration();
+            config.BasePath = "http://petstore.swagger.io:80/v2";
+            // Configure OAuth2 access token for authorization: petstore_auth
+            config.AccessToken = "YOUR_ACCESS_TOKEN";
+
+            var apiInstance = new PetApi(config);
+            var petId = 789L;  // long | ID of pet to update
+            var files = new List<System.IO.Stream>(); // List<System.IO.Stream> | 
+
+            try
+            {
+                // uploads an images
+                ApiResponse result = apiInstance.UploadFiles(petId, files);
+                Debug.WriteLine(result);
+            }
+            catch (ApiException  e)
+            {
+                Debug.Print("Exception when calling PetApi.UploadFiles: " + e.Message);
+                Debug.Print("Status Code: " + e.ErrorCode);
+                Debug.Print(e.StackTrace);
+            }
+        }
+    }
+}
+```
+
+#### Using the UploadFilesWithHttpInfo variant
+This returns an ApiResponse object which contains the response data, status code and headers.
+
+```csharp
+try
+{
+    // uploads an images
+    ApiResponse<ApiResponse> response = apiInstance.UploadFilesWithHttpInfo(petId, files);
+    Debug.Write("Status Code: " + response.StatusCode);
+    Debug.Write("Response Headers: " + response.Headers);
+    Debug.Write("Response Body: " + response.Data);
+}
+catch (ApiException e)
+{
+    Debug.Print("Exception when calling PetApi.UploadFilesWithHttpInfo: " + e.Message);
+    Debug.Print("Status Code: " + e.ErrorCode);
+    Debug.Print(e.StackTrace);
+}
+```
+
+### Parameters
+
+| Name | Type | Description | Notes |
+|------|------|-------------|-------|
+| **petId** | **long** | ID of pet to update |  |
+| **files** | **List&lt;System.IO.Stream&gt;** |  |  |
+
+### Return type
+
+[**ApiResponse**](ApiResponse.md)
+
+### Authorization
+
+[petstore_auth](../README.md#petstore_auth)
+
+### HTTP request headers
+
+ - **Content-Type**: multipart/form-data
+ - **Accept**: application/json
+
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **200** | successful operation |  -  |
+
+[[Back to top]](#) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to Model list]](../README.md#documentation-for-models) [[Back to README]](../README.md)
+
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Api/PetApi.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Api/PetApi.cs
index d6cbbc5133ed..8e0e14cc18dc 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Api/PetApi.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Api/PetApi.cs
@@ -232,6 +232,28 @@ public interface IPetApiSync : IApiAccessor
         /// <param name="operationIndex">Index associated with the operation.</param>
         /// <returns>ApiResponse of ApiResponse</returns>
         ApiResponse<ApiResponse> UploadFileWithRequiredFileWithHttpInfo(long petId, System.IO.Stream requiredFile, string additionalMetadata = default, int operationIndex = 0);
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="operationIndex">Index associated with the operation.</param>
+        /// <returns>ApiResponse</returns>
+        ApiResponse UploadFiles(long petId, List<System.IO.Stream> files, int operationIndex = 0);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="operationIndex">Index associated with the operation.</param>
+        /// <returns>ApiResponse of ApiResponse</returns>
+        ApiResponse<ApiResponse> UploadFilesWithHttpInfo(long petId, List<System.IO.Stream> files, int operationIndex = 0);
         #endregion Synchronous Operations
     }
 
@@ -482,6 +504,33 @@ public interface IPetApiAsync : IApiAccessor
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns>Task of ApiResponse (ApiResponse)</returns>
         System.Threading.Tasks.Task<ApiResponse<ApiResponse>> UploadFileWithRequiredFileWithHttpInfoAsync(long petId, System.IO.Stream requiredFile, string additionalMetadata = default, int operationIndex = 0, System.Threading.CancellationToken cancellationToken = default);
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="operationIndex">Index associated with the operation.</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns>Task of ApiResponse</returns>
+        System.Threading.Tasks.Task<ApiResponse> UploadFilesAsync(long petId, List<System.IO.Stream> files, int operationIndex = 0, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="operationIndex">Index associated with the operation.</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns>Task of ApiResponse (ApiResponse)</returns>
+        System.Threading.Tasks.Task<ApiResponse<ApiResponse>> UploadFilesWithHttpInfoAsync(long petId, List<System.IO.Stream> files, int operationIndex = 0, System.Threading.CancellationToken cancellationToken = default);
         #endregion Asynchronous Operations
     }
 
@@ -2351,5 +2400,196 @@ public async System.Threading.Tasks.Task<ApiResponse> UploadFileWithRequiredFile
             return localVarResponse;
         }
 
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="operationIndex">Index associated with the operation.</param>
+        /// <returns>ApiResponse</returns>
+        public ApiResponse UploadFiles(long petId, List<System.IO.Stream> files, int operationIndex = 0)
+        {
+            Org.OpenAPITools.Client.ApiResponse<ApiResponse> localVarResponse = UploadFilesWithHttpInfo(petId, files);
+            return localVarResponse.Data;
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="operationIndex">Index associated with the operation.</param>
+        /// <returns>ApiResponse of ApiResponse</returns>
+        public Org.OpenAPITools.Client.ApiResponse<ApiResponse> UploadFilesWithHttpInfo(long petId, List<System.IO.Stream> files, int operationIndex = 0)
+        {
+            // verify the required parameter 'files' is set
+            if (files == null)
+            {
+                throw new Org.OpenAPITools.Client.ApiException(400, "Missing required parameter 'files' when calling PetApi->UploadFiles");
+            }
+
+            Org.OpenAPITools.Client.RequestOptions localVarRequestOptions = new Org.OpenAPITools.Client.RequestOptions();
+
+            string[] _contentTypes = new string[] {
+                "multipart/form-data"
+            };
+
+            // to determine the Accept header
+            string[] _accepts = new string[] {
+                "application/json"
+            };
+
+            var localVarContentType = Org.OpenAPITools.Client.ClientUtils.SelectHeaderContentType(_contentTypes);
+            var localVarMultipartFormData = localVarContentType == "multipart/form-data";
+            if (localVarContentType != null)
+            {
+                localVarRequestOptions.HeaderParameters.Add("Content-Type", localVarContentType);
+            }
+
+            var localVarAccept = Org.OpenAPITools.Client.ClientUtils.SelectHeaderAccept(_accepts);
+            if (localVarAccept != null)
+            {
+                localVarRequestOptions.HeaderParameters.Add("Accept", localVarAccept);
+            }
+
+            localVarRequestOptions.PathParameters.Add("petId", Org.OpenAPITools.Client.ClientUtils.ParameterToString(petId)); // path parameter
+            foreach (var file in files)
+            {
+                localVarRequestOptions.FileParameters.Add("files", file);
+            }
+
+            localVarRequestOptions.Operation = "PetApi.UploadFiles";
+            localVarRequestOptions.OperationIndex = operationIndex;
+
+            // authentication (petstore_auth) required
+            // oauth required
+            if (!localVarRequestOptions.HeaderParameters.ContainsKey("Authorization"))
+            {
+                if (!string.IsNullOrEmpty(this.Configuration.AccessToken))
+                {
+                    localVarRequestOptions.HeaderParameters.Add("Authorization", "Bearer " + this.Configuration.AccessToken);
+                }
+                else if (!string.IsNullOrEmpty(this.Configuration.OAuthTokenUrl) &&
+                         !string.IsNullOrEmpty(this.Configuration.OAuthClientId) &&
+                         !string.IsNullOrEmpty(this.Configuration.OAuthClientSecret) &&
+                         this.Configuration.OAuthFlow != null)
+                {
+                    localVarRequestOptions.OAuth = true;
+                }
+            }
+
+            // make the HTTP request
+            var localVarResponse = this.Client.Post<ApiResponse>("/pet/{petId}/uploadImages", localVarRequestOptions, this.Configuration);
+            if (this.ExceptionFactory != null)
+            {
+                Exception _exception = this.ExceptionFactory("UploadFiles", localVarResponse);
+                if (_exception != null)
+                {
+                    throw _exception;
+                }
+            }
+
+            return localVarResponse;
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="operationIndex">Index associated with the operation.</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns>Task of ApiResponse</returns>
+        public async System.Threading.Tasks.Task<ApiResponse> UploadFilesAsync(long petId, List<System.IO.Stream> files, int operationIndex = 0, System.Threading.CancellationToken cancellationToken = default)
+        {
+            Org.OpenAPITools.Client.ApiResponse<ApiResponse> localVarResponse = await UploadFilesWithHttpInfoAsync(petId, files, operationIndex, cancellationToken).ConfigureAwait(false);
+            return localVarResponse.Data;
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="operationIndex">Index associated with the operation.</param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns>Task of ApiResponse (ApiResponse)</returns>
+        public async System.Threading.Tasks.Task<Org.OpenAPITools.Client.ApiResponse<ApiResponse>> UploadFilesWithHttpInfoAsync(long petId, List<System.IO.Stream> files, int operationIndex = 0, System.Threading.CancellationToken cancellationToken = default)
+        {
+            // verify the required parameter 'files' is set
+            if (files == null)
+            {
+                throw new Org.OpenAPITools.Client.ApiException(400, "Missing required parameter 'files' when calling PetApi->UploadFiles");
+            }
+
+
+            Org.OpenAPITools.Client.RequestOptions localVarRequestOptions = new Org.OpenAPITools.Client.RequestOptions();
+
+            string[] _contentTypes = new string[] {
+                "multipart/form-data"
+            };
+
+            // to determine the Accept header
+            string[] _accepts = new string[] {
+                "application/json"
+            };
+
+            var localVarContentType = Org.OpenAPITools.Client.ClientUtils.SelectHeaderContentType(_contentTypes);
+            if (localVarContentType != null)
+            {
+                localVarRequestOptions.HeaderParameters.Add("Content-Type", localVarContentType);
+            }
+
+            var localVarAccept = Org.OpenAPITools.Client.ClientUtils.SelectHeaderAccept(_accepts);
+            if (localVarAccept != null)
+            {
+                localVarRequestOptions.HeaderParameters.Add("Accept", localVarAccept);
+            }
+
+            localVarRequestOptions.PathParameters.Add("petId", Org.OpenAPITools.Client.ClientUtils.ParameterToString(petId)); // path parameter
+            foreach (var file in files)
+            {
+                localVarRequestOptions.FileParameters.Add("files", file);
+            }
+
+            localVarRequestOptions.Operation = "PetApi.UploadFiles";
+            localVarRequestOptions.OperationIndex = operationIndex;
+
+            // authentication (petstore_auth) required
+            // oauth required
+            if (!localVarRequestOptions.HeaderParameters.ContainsKey("Authorization"))
+            {
+                if (!string.IsNullOrEmpty(this.Configuration.AccessToken))
+                {
+                    localVarRequestOptions.HeaderParameters.Add("Authorization", "Bearer " + this.Configuration.AccessToken);
+                }
+                else if (!string.IsNullOrEmpty(this.Configuration.OAuthTokenUrl) &&
+                         !string.IsNullOrEmpty(this.Configuration.OAuthClientId) &&
+                         !string.IsNullOrEmpty(this.Configuration.OAuthClientSecret) &&
+                         this.Configuration.OAuthFlow != null)
+                {
+                    localVarRequestOptions.OAuth = true;
+                }
+            }
+
+            // make the HTTP request
+            var localVarResponse = await this.AsynchronousClient.PostAsync<ApiResponse>("/pet/{petId}/uploadImages", localVarRequestOptions, this.Configuration, cancellationToken).ConfigureAwait(false);
+
+            if (this.ExceptionFactory != null)
+            {
+                Exception _exception = this.ExceptionFactory("UploadFiles", localVarResponse);
+                if (_exception != null)
+                {
+                    throw _exception;
+                }
+            }
+
+            return localVarResponse;
+        }
+
     }
 }
diff --git a/samples/client/petstore/csharp/unityWebRequest/net10/Petstore/README.md b/samples/client/petstore/csharp/unityWebRequest/net10/Petstore/README.md
index 3e2173e6db41..f3a7c402bb1a 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net10/Petstore/README.md
+++ b/samples/client/petstore/csharp/unityWebRequest/net10/Petstore/README.md
@@ -127,6 +127,7 @@ Class | Method | HTTP request | Description
 *PetApi* | [**UpdatePetWithForm**](PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data
 *PetApi* | [**UploadFile**](PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image
 *PetApi* | [**UploadFileWithRequiredFile**](PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required)
+*PetApi* | [**UploadFiles**](PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images
 *StoreApi* | [**DeleteOrder**](StoreApi.md#deleteorder) | **DELETE** /store/order/{order_id} | Delete purchase order by ID
 *StoreApi* | [**GetInventory**](StoreApi.md#getinventory) | **GET** /store/inventory | Returns pet inventories by status
 *StoreApi* | [**GetOrderById**](StoreApi.md#getorderbyid) | **GET** /store/order/{order_id} | Find purchase order by ID
diff --git a/samples/client/petstore/csharp/unityWebRequest/net10/Petstore/api/openapi.yaml b/samples/client/petstore/csharp/unityWebRequest/net10/Petstore/api/openapi.yaml
index d8106a5755fc..ca451f3fb832 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net10/Petstore/api/openapi.yaml
+++ b/samples/client/petstore/csharp/unityWebRequest/net10/Petstore/api/openapi.yaml
@@ -331,6 +331,40 @@ paths:
       summary: uploads an image
       tags:
       - pet
+  /pet/{petId}/uploadImages:
+    post:
+      description: ""
+      operationId: uploadFiles
+      parameters:
+      - description: ID of pet to update
+        explode: false
+        in: path
+        name: petId
+        required: true
+        schema:
+          format: int64
+          type: integer
+        style: simple
+      requestBody:
+        content:
+          multipart/form-data:
+            schema:
+              $ref: "#/components/schemas/uploadFiles_request"
+        required: true
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ApiResponse"
+          description: successful operation
+      security:
+      - petstore_auth:
+        - write:pets
+        - read:pets
+      summary: uploads an images
+      tags:
+      - pet
   /store/inventory:
     get:
       description: Returns a map of status codes to quantities
@@ -2924,6 +2958,16 @@ components:
           format: binary
           type: string
       type: object
+    uploadFiles_request:
+      properties:
+        files:
+          items:
+            format: binary
+            type: string
+          type: array
+      required:
+      - files
+      type: object
     testEnumParameters_request:
       properties:
         enum_form_string_array:
diff --git a/samples/client/petstore/csharp/unityWebRequest/net10/Petstore/docs/PetApi.md b/samples/client/petstore/csharp/unityWebRequest/net10/Petstore/docs/PetApi.md
index 5272a0b102c3..829ca6d25184 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net10/Petstore/docs/PetApi.md
+++ b/samples/client/petstore/csharp/unityWebRequest/net10/Petstore/docs/PetApi.md
@@ -13,6 +13,7 @@ All URIs are relative to *http://petstore.swagger.io:80/v2*
 | [**UpdatePetWithForm**](PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data |
 | [**UploadFile**](PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image |
 | [**UploadFileWithRequiredFile**](PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required) |
+| [**UploadFiles**](PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images |
 
 <a id="addpet"></a>
 # **AddPet**
@@ -860,3 +861,97 @@ catch (ApiException e)
 
 [[Back to top]](#) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to Model list]](../README.md#documentation-for-models) [[Back to README]](../README.md)
 
+<a id="uploadfiles"></a>
+# **UploadFiles**
+> ApiResponse UploadFiles (long petId, List<System.IO.Stream> files)
+
+uploads an images
+
+### Example
+```csharp
+using System.Collections.Generic;
+using System.Diagnostics;
+using Org.OpenAPITools.Api;
+using Org.OpenAPITools.Client;
+using Org.OpenAPITools.Model;
+
+namespace Example
+{
+    public class UploadFilesExample
+    {
+        public static void Main()
+        {
+            Configuration config = new Configuration();
+            config.BasePath = "http://petstore.swagger.io:80/v2";
+            // Configure OAuth2 access token for authorization: petstore_auth
+            config.AccessToken = "YOUR_ACCESS_TOKEN";
+
+            var apiInstance = new PetApi(config);
+            var petId = 789L;  // long | ID of pet to update
+            var files = new List<System.IO.Stream>(); // List<System.IO.Stream> | 
+
+            try
+            {
+                // uploads an images
+                ApiResponse result = apiInstance.UploadFiles(petId, files);
+                Debug.WriteLine(result);
+            }
+            catch (ApiException  e)
+            {
+                Debug.Print("Exception when calling PetApi.UploadFiles: " + e.Message);
+                Debug.Print("Status Code: " + e.ErrorCode);
+                Debug.Print(e.StackTrace);
+            }
+        }
+    }
+}
+```
+
+#### Using the UploadFilesWithHttpInfo variant
+This returns an ApiResponse object which contains the response data, status code and headers.
+
+```csharp
+try
+{
+    // uploads an images
+    ApiResponse<ApiResponse> response = apiInstance.UploadFilesWithHttpInfo(petId, files);
+    Debug.Write("Status Code: " + response.StatusCode);
+    Debug.Write("Response Headers: " + response.Headers);
+    Debug.Write("Response Body: " + response.Data);
+}
+catch (ApiException e)
+{
+    Debug.Print("Exception when calling PetApi.UploadFilesWithHttpInfo: " + e.Message);
+    Debug.Print("Status Code: " + e.ErrorCode);
+    Debug.Print(e.StackTrace);
+}
+```
+
+### Parameters
+
+| Name | Type | Description | Notes |
+|------|------|-------------|-------|
+| **petId** | **long** | ID of pet to update |  |
+| **files** | **List&lt;System.IO.Stream&gt;** |  |  |
+
+### Return type
+
+[**ApiResponse**](ApiResponse.md)
+
+### Authorization
+
+[petstore_auth](../README.md#petstore_auth)
+
+### HTTP request headers
+
+ - **Content-Type**: multipart/form-data
+ - **Accept**: application/json
+
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **200** | successful operation |  -  |
+
+[[Back to top]](#) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to Model list]](../README.md#documentation-for-models) [[Back to README]](../README.md)
+
diff --git a/samples/client/petstore/csharp/unityWebRequest/net10/Petstore/src/Org.OpenAPITools/Api/PetApi.cs b/samples/client/petstore/csharp/unityWebRequest/net10/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
index 2c624280f114..d23685664bc2 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net10/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net10/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
@@ -213,6 +213,26 @@ public interface IPetApiSync : IApiAccessor
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <returns>ApiResponse of ApiResponse</returns>
         ApiResponse<ApiResponse> UploadFileWithRequiredFileWithHttpInfo(long petId, System.IO.Stream requiredFile, string? additionalMetadata = default);
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <returns>ApiResponse</returns>
+        ApiResponse UploadFiles(long petId, List<System.IO.Stream> files);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <returns>ApiResponse of ApiResponse</returns>
+        ApiResponse<ApiResponse> UploadFilesWithHttpInfo(long petId, List<System.IO.Stream> files);
         #endregion Synchronous Operations
     }
 
@@ -445,6 +465,31 @@ public interface IPetApiAsync : IApiAccessor
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns>Task of ApiResponse (ApiResponse)</returns>
         System.Threading.Tasks.Task<ApiResponse<ApiResponse>> UploadFileWithRequiredFileWithHttpInfoAsync(long petId, System.IO.Stream requiredFile, string? additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns>Task of ApiResponse</returns>
+        System.Threading.Tasks.Task<ApiResponse> UploadFilesAsync(long petId, List<System.IO.Stream> files, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns>Task of ApiResponse (ApiResponse)</returns>
+        System.Threading.Tasks.Task<ApiResponse<ApiResponse>> UploadFilesWithHttpInfoAsync(long petId, List<System.IO.Stream> files, System.Threading.CancellationToken cancellationToken = default);
         #endregion Asynchronous Operations
     }
 
@@ -2019,5 +2064,149 @@ public async System.Threading.Tasks.Task<ApiResponse> UploadFileWithRequiredFile
             return localVarResponse;
         }
 
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <returns>ApiResponse</returns>
+        public ApiResponse UploadFiles(long petId, List<System.IO.Stream> files)
+        {
+            Org.OpenAPITools.Client.ApiResponse<ApiResponse> localVarResponse = UploadFilesWithHttpInfo(petId, files);
+            return localVarResponse.Data;
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <returns>ApiResponse of ApiResponse</returns>
+        public Org.OpenAPITools.Client.ApiResponse<ApiResponse> UploadFilesWithHttpInfo(long petId, List<System.IO.Stream> files)
+        {
+            // verify the required parameter 'files' is set
+            if (files == null)
+                throw new Org.OpenAPITools.Client.ApiException(400, "Missing required parameter 'files' when calling PetApi->UploadFiles");
+
+            Org.OpenAPITools.Client.RequestOptions localVarRequestOptions = new Org.OpenAPITools.Client.RequestOptions();
+
+            string[] _contentTypes = new string[] {
+                "multipart/form-data"
+            };
+
+            // to determine the Accept header
+            string[] _accepts = new string[] {
+                "application/json"
+            };
+
+            var localVarContentType = Org.OpenAPITools.Client.ClientUtils.SelectHeaderContentType(_contentTypes);
+            if (localVarContentType != null) localVarRequestOptions.HeaderParameters.Add("Content-Type", localVarContentType);
+
+            var localVarAccept = Org.OpenAPITools.Client.ClientUtils.SelectHeaderAccept(_accepts);
+            if (localVarAccept != null) localVarRequestOptions.HeaderParameters.Add("Accept", localVarAccept);
+
+            localVarRequestOptions.PathParameters.Add("petId", Org.OpenAPITools.Client.ClientUtils.ParameterToString(petId)); // path parameter
+
+            // authentication (petstore_auth) required
+            // oauth required
+            if (!string.IsNullOrEmpty(this.Configuration.AccessToken) && !localVarRequestOptions.HeaderParameters.ContainsKey("Authorization"))
+            {
+                localVarRequestOptions.HeaderParameters.Add("Authorization", "Bearer " + this.Configuration.AccessToken);
+            }
+
+            // make the HTTP request
+            var localVarResponse = this.Client.Post<ApiResponse>("/pet/{petId}/uploadImages", localVarRequestOptions, this.Configuration);
+
+            if (this.ExceptionFactory != null)
+            {
+                Exception _exception = this.ExceptionFactory("UploadFiles", localVarResponse);
+                if (_exception != null) throw _exception;
+            }
+
+            return localVarResponse;
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns>Task of ApiResponse</returns>
+        public async System.Threading.Tasks.Task<ApiResponse> UploadFilesAsync(long petId, List<System.IO.Stream> files, System.Threading.CancellationToken cancellationToken = default)
+        {
+            var task = UploadFilesWithHttpInfoAsync(petId, files, cancellationToken);
+#if UNITY_EDITOR || !UNITY_WEBGL
+            Org.OpenAPITools.Client.ApiResponse<ApiResponse> localVarResponse = await task.ConfigureAwait(false);
+#else
+            Org.OpenAPITools.Client.ApiResponse<ApiResponse> localVarResponse = await task;
+#endif
+            return localVarResponse.Data;
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns>Task of ApiResponse (ApiResponse)</returns>
+        public async System.Threading.Tasks.Task<Org.OpenAPITools.Client.ApiResponse<ApiResponse>> UploadFilesWithHttpInfoAsync(long petId, List<System.IO.Stream> files, System.Threading.CancellationToken cancellationToken = default)
+        {
+            // verify the required parameter 'files' is set
+            if (files == null)
+                throw new Org.OpenAPITools.Client.ApiException(400, "Missing required parameter 'files' when calling PetApi->UploadFiles");
+
+
+            Org.OpenAPITools.Client.RequestOptions localVarRequestOptions = new Org.OpenAPITools.Client.RequestOptions();
+
+            string[] _contentTypes = new string[] {
+                "multipart/form-data"
+            };
+
+            // to determine the Accept header
+            string[] _accepts = new string[] {
+                "application/json"
+            };
+
+
+            var localVarContentType = Org.OpenAPITools.Client.ClientUtils.SelectHeaderContentType(_contentTypes);
+            if (localVarContentType != null) localVarRequestOptions.HeaderParameters.Add("Content-Type", localVarContentType);
+
+            var localVarAccept = Org.OpenAPITools.Client.ClientUtils.SelectHeaderAccept(_accepts);
+            if (localVarAccept != null) localVarRequestOptions.HeaderParameters.Add("Accept", localVarAccept);
+
+            localVarRequestOptions.PathParameters.Add("petId", Org.OpenAPITools.Client.ClientUtils.ParameterToString(petId)); // path parameter
+
+            // authentication (petstore_auth) required
+            // oauth required
+            if (!string.IsNullOrEmpty(this.Configuration.AccessToken) && !localVarRequestOptions.HeaderParameters.ContainsKey("Authorization"))
+            {
+                localVarRequestOptions.HeaderParameters.Add("Authorization", "Bearer " + this.Configuration.AccessToken);
+            }
+
+            // make the HTTP request
+
+            var task = this.AsynchronousClient.PostAsync<ApiResponse>("/pet/{petId}/uploadImages", localVarRequestOptions, this.Configuration, cancellationToken);
+
+#if UNITY_EDITOR || !UNITY_WEBGL
+            var localVarResponse = await task.ConfigureAwait(false);
+#else
+            var localVarResponse = await task;
+#endif
+
+            if (this.ExceptionFactory != null)
+            {
+                Exception _exception = this.ExceptionFactory("UploadFiles", localVarResponse);
+                if (_exception != null) throw _exception;
+            }
+
+            return localVarResponse;
+        }
+
     }
 }
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/README.md b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/README.md
index 3e2173e6db41..f3a7c402bb1a 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/README.md
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/README.md
@@ -127,6 +127,7 @@ Class | Method | HTTP request | Description
 *PetApi* | [**UpdatePetWithForm**](PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data
 *PetApi* | [**UploadFile**](PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image
 *PetApi* | [**UploadFileWithRequiredFile**](PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required)
+*PetApi* | [**UploadFiles**](PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images
 *StoreApi* | [**DeleteOrder**](StoreApi.md#deleteorder) | **DELETE** /store/order/{order_id} | Delete purchase order by ID
 *StoreApi* | [**GetInventory**](StoreApi.md#getinventory) | **GET** /store/inventory | Returns pet inventories by status
 *StoreApi* | [**GetOrderById**](StoreApi.md#getorderbyid) | **GET** /store/order/{order_id} | Find purchase order by ID
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/api/openapi.yaml b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/api/openapi.yaml
index d8106a5755fc..ca451f3fb832 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/api/openapi.yaml
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/api/openapi.yaml
@@ -331,6 +331,40 @@ paths:
       summary: uploads an image
       tags:
       - pet
+  /pet/{petId}/uploadImages:
+    post:
+      description: ""
+      operationId: uploadFiles
+      parameters:
+      - description: ID of pet to update
+        explode: false
+        in: path
+        name: petId
+        required: true
+        schema:
+          format: int64
+          type: integer
+        style: simple
+      requestBody:
+        content:
+          multipart/form-data:
+            schema:
+              $ref: "#/components/schemas/uploadFiles_request"
+        required: true
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ApiResponse"
+          description: successful operation
+      security:
+      - petstore_auth:
+        - write:pets
+        - read:pets
+      summary: uploads an images
+      tags:
+      - pet
   /store/inventory:
     get:
       description: Returns a map of status codes to quantities
@@ -2924,6 +2958,16 @@ components:
           format: binary
           type: string
       type: object
+    uploadFiles_request:
+      properties:
+        files:
+          items:
+            format: binary
+            type: string
+          type: array
+      required:
+      - files
+      type: object
     testEnumParameters_request:
       properties:
         enum_form_string_array:
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/docs/PetApi.md b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/docs/PetApi.md
index 5272a0b102c3..829ca6d25184 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/docs/PetApi.md
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/docs/PetApi.md
@@ -13,6 +13,7 @@ All URIs are relative to *http://petstore.swagger.io:80/v2*
 | [**UpdatePetWithForm**](PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data |
 | [**UploadFile**](PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image |
 | [**UploadFileWithRequiredFile**](PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required) |
+| [**UploadFiles**](PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images |
 
 <a id="addpet"></a>
 # **AddPet**
@@ -860,3 +861,97 @@ catch (ApiException e)
 
 [[Back to top]](#) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to Model list]](../README.md#documentation-for-models) [[Back to README]](../README.md)
 
+<a id="uploadfiles"></a>
+# **UploadFiles**
+> ApiResponse UploadFiles (long petId, List<System.IO.Stream> files)
+
+uploads an images
+
+### Example
+```csharp
+using System.Collections.Generic;
+using System.Diagnostics;
+using Org.OpenAPITools.Api;
+using Org.OpenAPITools.Client;
+using Org.OpenAPITools.Model;
+
+namespace Example
+{
+    public class UploadFilesExample
+    {
+        public static void Main()
+        {
+            Configuration config = new Configuration();
+            config.BasePath = "http://petstore.swagger.io:80/v2";
+            // Configure OAuth2 access token for authorization: petstore_auth
+            config.AccessToken = "YOUR_ACCESS_TOKEN";
+
+            var apiInstance = new PetApi(config);
+            var petId = 789L;  // long | ID of pet to update
+            var files = new List<System.IO.Stream>(); // List<System.IO.Stream> | 
+
+            try
+            {
+                // uploads an images
+                ApiResponse result = apiInstance.UploadFiles(petId, files);
+                Debug.WriteLine(result);
+            }
+            catch (ApiException  e)
+            {
+                Debug.Print("Exception when calling PetApi.UploadFiles: " + e.Message);
+                Debug.Print("Status Code: " + e.ErrorCode);
+                Debug.Print(e.StackTrace);
+            }
+        }
+    }
+}
+```
+
+#### Using the UploadFilesWithHttpInfo variant
+This returns an ApiResponse object which contains the response data, status code and headers.
+
+```csharp
+try
+{
+    // uploads an images
+    ApiResponse<ApiResponse> response = apiInstance.UploadFilesWithHttpInfo(petId, files);
+    Debug.Write("Status Code: " + response.StatusCode);
+    Debug.Write("Response Headers: " + response.Headers);
+    Debug.Write("Response Body: " + response.Data);
+}
+catch (ApiException e)
+{
+    Debug.Print("Exception when calling PetApi.UploadFilesWithHttpInfo: " + e.Message);
+    Debug.Print("Status Code: " + e.ErrorCode);
+    Debug.Print(e.StackTrace);
+}
+```
+
+### Parameters
+
+| Name | Type | Description | Notes |
+|------|------|-------------|-------|
+| **petId** | **long** | ID of pet to update |  |
+| **files** | **List&lt;System.IO.Stream&gt;** |  |  |
+
+### Return type
+
+[**ApiResponse**](ApiResponse.md)
+
+### Authorization
+
+[petstore_auth](../README.md#petstore_auth)
+
+### HTTP request headers
+
+ - **Content-Type**: multipart/form-data
+ - **Accept**: application/json
+
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **200** | successful operation |  -  |
+
+[[Back to top]](#) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to Model list]](../README.md#documentation-for-models) [[Back to README]](../README.md)
+
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Api/PetApi.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
index 2c624280f114..d23685664bc2 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
@@ -213,6 +213,26 @@ public interface IPetApiSync : IApiAccessor
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <returns>ApiResponse of ApiResponse</returns>
         ApiResponse<ApiResponse> UploadFileWithRequiredFileWithHttpInfo(long petId, System.IO.Stream requiredFile, string? additionalMetadata = default);
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <returns>ApiResponse</returns>
+        ApiResponse UploadFiles(long petId, List<System.IO.Stream> files);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <returns>ApiResponse of ApiResponse</returns>
+        ApiResponse<ApiResponse> UploadFilesWithHttpInfo(long petId, List<System.IO.Stream> files);
         #endregion Synchronous Operations
     }
 
@@ -445,6 +465,31 @@ public interface IPetApiAsync : IApiAccessor
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns>Task of ApiResponse (ApiResponse)</returns>
         System.Threading.Tasks.Task<ApiResponse<ApiResponse>> UploadFileWithRequiredFileWithHttpInfoAsync(long petId, System.IO.Stream requiredFile, string? additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns>Task of ApiResponse</returns>
+        System.Threading.Tasks.Task<ApiResponse> UploadFilesAsync(long petId, List<System.IO.Stream> files, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns>Task of ApiResponse (ApiResponse)</returns>
+        System.Threading.Tasks.Task<ApiResponse<ApiResponse>> UploadFilesWithHttpInfoAsync(long petId, List<System.IO.Stream> files, System.Threading.CancellationToken cancellationToken = default);
         #endregion Asynchronous Operations
     }
 
@@ -2019,5 +2064,149 @@ public async System.Threading.Tasks.Task<ApiResponse> UploadFileWithRequiredFile
             return localVarResponse;
         }
 
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <returns>ApiResponse</returns>
+        public ApiResponse UploadFiles(long petId, List<System.IO.Stream> files)
+        {
+            Org.OpenAPITools.Client.ApiResponse<ApiResponse> localVarResponse = UploadFilesWithHttpInfo(petId, files);
+            return localVarResponse.Data;
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <returns>ApiResponse of ApiResponse</returns>
+        public Org.OpenAPITools.Client.ApiResponse<ApiResponse> UploadFilesWithHttpInfo(long petId, List<System.IO.Stream> files)
+        {
+            // verify the required parameter 'files' is set
+            if (files == null)
+                throw new Org.OpenAPITools.Client.ApiException(400, "Missing required parameter 'files' when calling PetApi->UploadFiles");
+
+            Org.OpenAPITools.Client.RequestOptions localVarRequestOptions = new Org.OpenAPITools.Client.RequestOptions();
+
+            string[] _contentTypes = new string[] {
+                "multipart/form-data"
+            };
+
+            // to determine the Accept header
+            string[] _accepts = new string[] {
+                "application/json"
+            };
+
+            var localVarContentType = Org.OpenAPITools.Client.ClientUtils.SelectHeaderContentType(_contentTypes);
+            if (localVarContentType != null) localVarRequestOptions.HeaderParameters.Add("Content-Type", localVarContentType);
+
+            var localVarAccept = Org.OpenAPITools.Client.ClientUtils.SelectHeaderAccept(_accepts);
+            if (localVarAccept != null) localVarRequestOptions.HeaderParameters.Add("Accept", localVarAccept);
+
+            localVarRequestOptions.PathParameters.Add("petId", Org.OpenAPITools.Client.ClientUtils.ParameterToString(petId)); // path parameter
+
+            // authentication (petstore_auth) required
+            // oauth required
+            if (!string.IsNullOrEmpty(this.Configuration.AccessToken) && !localVarRequestOptions.HeaderParameters.ContainsKey("Authorization"))
+            {
+                localVarRequestOptions.HeaderParameters.Add("Authorization", "Bearer " + this.Configuration.AccessToken);
+            }
+
+            // make the HTTP request
+            var localVarResponse = this.Client.Post<ApiResponse>("/pet/{petId}/uploadImages", localVarRequestOptions, this.Configuration);
+
+            if (this.ExceptionFactory != null)
+            {
+                Exception _exception = this.ExceptionFactory("UploadFiles", localVarResponse);
+                if (_exception != null) throw _exception;
+            }
+
+            return localVarResponse;
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns>Task of ApiResponse</returns>
+        public async System.Threading.Tasks.Task<ApiResponse> UploadFilesAsync(long petId, List<System.IO.Stream> files, System.Threading.CancellationToken cancellationToken = default)
+        {
+            var task = UploadFilesWithHttpInfoAsync(petId, files, cancellationToken);
+#if UNITY_EDITOR || !UNITY_WEBGL
+            Org.OpenAPITools.Client.ApiResponse<ApiResponse> localVarResponse = await task.ConfigureAwait(false);
+#else
+            Org.OpenAPITools.Client.ApiResponse<ApiResponse> localVarResponse = await task;
+#endif
+            return localVarResponse.Data;
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns>Task of ApiResponse (ApiResponse)</returns>
+        public async System.Threading.Tasks.Task<Org.OpenAPITools.Client.ApiResponse<ApiResponse>> UploadFilesWithHttpInfoAsync(long petId, List<System.IO.Stream> files, System.Threading.CancellationToken cancellationToken = default)
+        {
+            // verify the required parameter 'files' is set
+            if (files == null)
+                throw new Org.OpenAPITools.Client.ApiException(400, "Missing required parameter 'files' when calling PetApi->UploadFiles");
+
+
+            Org.OpenAPITools.Client.RequestOptions localVarRequestOptions = new Org.OpenAPITools.Client.RequestOptions();
+
+            string[] _contentTypes = new string[] {
+                "multipart/form-data"
+            };
+
+            // to determine the Accept header
+            string[] _accepts = new string[] {
+                "application/json"
+            };
+
+
+            var localVarContentType = Org.OpenAPITools.Client.ClientUtils.SelectHeaderContentType(_contentTypes);
+            if (localVarContentType != null) localVarRequestOptions.HeaderParameters.Add("Content-Type", localVarContentType);
+
+            var localVarAccept = Org.OpenAPITools.Client.ClientUtils.SelectHeaderAccept(_accepts);
+            if (localVarAccept != null) localVarRequestOptions.HeaderParameters.Add("Accept", localVarAccept);
+
+            localVarRequestOptions.PathParameters.Add("petId", Org.OpenAPITools.Client.ClientUtils.ParameterToString(petId)); // path parameter
+
+            // authentication (petstore_auth) required
+            // oauth required
+            if (!string.IsNullOrEmpty(this.Configuration.AccessToken) && !localVarRequestOptions.HeaderParameters.ContainsKey("Authorization"))
+            {
+                localVarRequestOptions.HeaderParameters.Add("Authorization", "Bearer " + this.Configuration.AccessToken);
+            }
+
+            // make the HTTP request
+
+            var task = this.AsynchronousClient.PostAsync<ApiResponse>("/pet/{petId}/uploadImages", localVarRequestOptions, this.Configuration, cancellationToken);
+
+#if UNITY_EDITOR || !UNITY_WEBGL
+            var localVarResponse = await task.ConfigureAwait(false);
+#else
+            var localVarResponse = await task;
+#endif
+
+            if (this.ExceptionFactory != null)
+            {
+                Exception _exception = this.ExceptionFactory("UploadFiles", localVarResponse);
+                if (_exception != null) throw _exception;
+            }
+
+            return localVarResponse;
+        }
+
     }
 }
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/README.md b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/README.md
index 3e2173e6db41..f3a7c402bb1a 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/README.md
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/README.md
@@ -127,6 +127,7 @@ Class | Method | HTTP request | Description
 *PetApi* | [**UpdatePetWithForm**](PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data
 *PetApi* | [**UploadFile**](PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image
 *PetApi* | [**UploadFileWithRequiredFile**](PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required)
+*PetApi* | [**UploadFiles**](PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images
 *StoreApi* | [**DeleteOrder**](StoreApi.md#deleteorder) | **DELETE** /store/order/{order_id} | Delete purchase order by ID
 *StoreApi* | [**GetInventory**](StoreApi.md#getinventory) | **GET** /store/inventory | Returns pet inventories by status
 *StoreApi* | [**GetOrderById**](StoreApi.md#getorderbyid) | **GET** /store/order/{order_id} | Find purchase order by ID
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/api/openapi.yaml b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/api/openapi.yaml
index d8106a5755fc..ca451f3fb832 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/api/openapi.yaml
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/api/openapi.yaml
@@ -331,6 +331,40 @@ paths:
       summary: uploads an image
       tags:
       - pet
+  /pet/{petId}/uploadImages:
+    post:
+      description: ""
+      operationId: uploadFiles
+      parameters:
+      - description: ID of pet to update
+        explode: false
+        in: path
+        name: petId
+        required: true
+        schema:
+          format: int64
+          type: integer
+        style: simple
+      requestBody:
+        content:
+          multipart/form-data:
+            schema:
+              $ref: "#/components/schemas/uploadFiles_request"
+        required: true
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ApiResponse"
+          description: successful operation
+      security:
+      - petstore_auth:
+        - write:pets
+        - read:pets
+      summary: uploads an images
+      tags:
+      - pet
   /store/inventory:
     get:
       description: Returns a map of status codes to quantities
@@ -2924,6 +2958,16 @@ components:
           format: binary
           type: string
       type: object
+    uploadFiles_request:
+      properties:
+        files:
+          items:
+            format: binary
+            type: string
+          type: array
+      required:
+      - files
+      type: object
     testEnumParameters_request:
       properties:
         enum_form_string_array:
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/docs/PetApi.md b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/docs/PetApi.md
index 3db7da1cd2fa..cb3a65d239b4 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/docs/PetApi.md
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/docs/PetApi.md
@@ -13,6 +13,7 @@ All URIs are relative to *http://petstore.swagger.io:80/v2*
 | [**UpdatePetWithForm**](PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data |
 | [**UploadFile**](PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image |
 | [**UploadFileWithRequiredFile**](PetApi.md#uploadfilewithrequiredfile) | **POST** /fake/{petId}/uploadImageWithRequiredFile | uploads an image (required) |
+| [**UploadFiles**](PetApi.md#uploadfiles) | **POST** /pet/{petId}/uploadImages | uploads an images |
 
 <a id="addpet"></a>
 # **AddPet**
@@ -860,3 +861,97 @@ catch (ApiException e)
 
 [[Back to top]](#) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to Model list]](../README.md#documentation-for-models) [[Back to README]](../README.md)
 
+<a id="uploadfiles"></a>
+# **UploadFiles**
+> ApiResponse UploadFiles (long petId, List<System.IO.Stream> files)
+
+uploads an images
+
+### Example
+```csharp
+using System.Collections.Generic;
+using System.Diagnostics;
+using Org.OpenAPITools.Api;
+using Org.OpenAPITools.Client;
+using Org.OpenAPITools.Model;
+
+namespace Example
+{
+    public class UploadFilesExample
+    {
+        public static void Main()
+        {
+            Configuration config = new Configuration();
+            config.BasePath = "http://petstore.swagger.io:80/v2";
+            // Configure OAuth2 access token for authorization: petstore_auth
+            config.AccessToken = "YOUR_ACCESS_TOKEN";
+
+            var apiInstance = new PetApi(config);
+            var petId = 789L;  // long | ID of pet to update
+            var files = new List<System.IO.Stream>(); // List<System.IO.Stream> | 
+
+            try
+            {
+                // uploads an images
+                ApiResponse result = apiInstance.UploadFiles(petId, files);
+                Debug.WriteLine(result);
+            }
+            catch (ApiException  e)
+            {
+                Debug.Print("Exception when calling PetApi.UploadFiles: " + e.Message);
+                Debug.Print("Status Code: " + e.ErrorCode);
+                Debug.Print(e.StackTrace);
+            }
+        }
+    }
+}
+```
+
+#### Using the UploadFilesWithHttpInfo variant
+This returns an ApiResponse object which contains the response data, status code and headers.
+
+```csharp
+try
+{
+    // uploads an images
+    ApiResponse<ApiResponse> response = apiInstance.UploadFilesWithHttpInfo(petId, files);
+    Debug.Write("Status Code: " + response.StatusCode);
+    Debug.Write("Response Headers: " + response.Headers);
+    Debug.Write("Response Body: " + response.Data);
+}
+catch (ApiException e)
+{
+    Debug.Print("Exception when calling PetApi.UploadFilesWithHttpInfo: " + e.Message);
+    Debug.Print("Status Code: " + e.ErrorCode);
+    Debug.Print(e.StackTrace);
+}
+```
+
+### Parameters
+
+| Name | Type | Description | Notes |
+|------|------|-------------|-------|
+| **petId** | **long** | ID of pet to update |  |
+| **files** | **List&lt;System.IO.Stream&gt;** |  |  |
+
+### Return type
+
+[**ApiResponse**](ApiResponse.md)
+
+### Authorization
+
+[petstore_auth](../README.md#petstore_auth)
+
+### HTTP request headers
+
+ - **Content-Type**: multipart/form-data
+ - **Accept**: application/json
+
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **200** | successful operation |  -  |
+
+[[Back to top]](#) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to Model list]](../README.md#documentation-for-models) [[Back to README]](../README.md)
+
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Api/PetApi.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
index 91f1a9769b50..767573545c91 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Api/PetApi.cs
@@ -213,6 +213,26 @@ public interface IPetApiSync : IApiAccessor
         /// <param name="additionalMetadata">Additional data to pass to server (optional)</param>
         /// <returns>ApiResponse of ApiResponse</returns>
         ApiResponse<ApiResponse> UploadFileWithRequiredFileWithHttpInfo(long petId, System.IO.Stream requiredFile, string additionalMetadata = default);
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <returns>ApiResponse</returns>
+        ApiResponse UploadFiles(long petId, List<System.IO.Stream> files);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <returns>ApiResponse of ApiResponse</returns>
+        ApiResponse<ApiResponse> UploadFilesWithHttpInfo(long petId, List<System.IO.Stream> files);
         #endregion Synchronous Operations
     }
 
@@ -445,6 +465,31 @@ public interface IPetApiAsync : IApiAccessor
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns>Task of ApiResponse (ApiResponse)</returns>
         System.Threading.Tasks.Task<ApiResponse<ApiResponse>> UploadFileWithRequiredFileWithHttpInfoAsync(long petId, System.IO.Stream requiredFile, string additionalMetadata = default, System.Threading.CancellationToken cancellationToken = default);
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns>Task of ApiResponse</returns>
+        System.Threading.Tasks.Task<ApiResponse> UploadFilesAsync(long petId, List<System.IO.Stream> files, System.Threading.CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// uploads an images
+        /// </summary>
+        /// <remarks>
+        /// 
+        /// </remarks>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns>Task of ApiResponse (ApiResponse)</returns>
+        System.Threading.Tasks.Task<ApiResponse<ApiResponse>> UploadFilesWithHttpInfoAsync(long petId, List<System.IO.Stream> files, System.Threading.CancellationToken cancellationToken = default);
         #endregion Asynchronous Operations
     }
 
@@ -2019,5 +2064,149 @@ public async System.Threading.Tasks.Task<ApiResponse> UploadFileWithRequiredFile
             return localVarResponse;
         }
 
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <returns>ApiResponse</returns>
+        public ApiResponse UploadFiles(long petId, List<System.IO.Stream> files)
+        {
+            Org.OpenAPITools.Client.ApiResponse<ApiResponse> localVarResponse = UploadFilesWithHttpInfo(petId, files);
+            return localVarResponse.Data;
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <returns>ApiResponse of ApiResponse</returns>
+        public Org.OpenAPITools.Client.ApiResponse<ApiResponse> UploadFilesWithHttpInfo(long petId, List<System.IO.Stream> files)
+        {
+            // verify the required parameter 'files' is set
+            if (files == null)
+                throw new Org.OpenAPITools.Client.ApiException(400, "Missing required parameter 'files' when calling PetApi->UploadFiles");
+
+            Org.OpenAPITools.Client.RequestOptions localVarRequestOptions = new Org.OpenAPITools.Client.RequestOptions();
+
+            string[] _contentTypes = new string[] {
+                "multipart/form-data"
+            };
+
+            // to determine the Accept header
+            string[] _accepts = new string[] {
+                "application/json"
+            };
+
+            var localVarContentType = Org.OpenAPITools.Client.ClientUtils.SelectHeaderContentType(_contentTypes);
+            if (localVarContentType != null) localVarRequestOptions.HeaderParameters.Add("Content-Type", localVarContentType);
+
+            var localVarAccept = Org.OpenAPITools.Client.ClientUtils.SelectHeaderAccept(_accepts);
+            if (localVarAccept != null) localVarRequestOptions.HeaderParameters.Add("Accept", localVarAccept);
+
+            localVarRequestOptions.PathParameters.Add("petId", Org.OpenAPITools.Client.ClientUtils.ParameterToString(petId)); // path parameter
+
+            // authentication (petstore_auth) required
+            // oauth required
+            if (!string.IsNullOrEmpty(this.Configuration.AccessToken) && !localVarRequestOptions.HeaderParameters.ContainsKey("Authorization"))
+            {
+                localVarRequestOptions.HeaderParameters.Add("Authorization", "Bearer " + this.Configuration.AccessToken);
+            }
+
+            // make the HTTP request
+            var localVarResponse = this.Client.Post<ApiResponse>("/pet/{petId}/uploadImages", localVarRequestOptions, this.Configuration);
+
+            if (this.ExceptionFactory != null)
+            {
+                Exception _exception = this.ExceptionFactory("UploadFiles", localVarResponse);
+                if (_exception != null) throw _exception;
+            }
+
+            return localVarResponse;
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns>Task of ApiResponse</returns>
+        public async System.Threading.Tasks.Task<ApiResponse> UploadFilesAsync(long petId, List<System.IO.Stream> files, System.Threading.CancellationToken cancellationToken = default)
+        {
+            var task = UploadFilesWithHttpInfoAsync(petId, files, cancellationToken);
+#if UNITY_EDITOR || !UNITY_WEBGL
+            Org.OpenAPITools.Client.ApiResponse<ApiResponse> localVarResponse = await task.ConfigureAwait(false);
+#else
+            Org.OpenAPITools.Client.ApiResponse<ApiResponse> localVarResponse = await task;
+#endif
+            return localVarResponse.Data;
+        }
+
+        /// <summary>
+        /// uploads an images 
+        /// </summary>
+        /// <exception cref="Org.OpenAPITools.Client.ApiException">Thrown when fails to make API call</exception>
+        /// <param name="petId">ID of pet to update</param>
+        /// <param name="files"></param>
+        /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
+        /// <returns>Task of ApiResponse (ApiResponse)</returns>
+        public async System.Threading.Tasks.Task<Org.OpenAPITools.Client.ApiResponse<ApiResponse>> UploadFilesWithHttpInfoAsync(long petId, List<System.IO.Stream> files, System.Threading.CancellationToken cancellationToken = default)
+        {
+            // verify the required parameter 'files' is set
+            if (files == null)
+                throw new Org.OpenAPITools.Client.ApiException(400, "Missing required parameter 'files' when calling PetApi->UploadFiles");
+
+
+            Org.OpenAPITools.Client.RequestOptions localVarRequestOptions = new Org.OpenAPITools.Client.RequestOptions();
+
+            string[] _contentTypes = new string[] {
+                "multipart/form-data"
+            };
+
+            // to determine the Accept header
+            string[] _accepts = new string[] {
+                "application/json"
+            };
+
+
+            var localVarContentType = Org.OpenAPITools.Client.ClientUtils.SelectHeaderContentType(_contentTypes);
+            if (localVarContentType != null) localVarRequestOptions.HeaderParameters.Add("Content-Type", localVarContentType);
+
+            var localVarAccept = Org.OpenAPITools.Client.ClientUtils.SelectHeaderAccept(_accepts);
+            if (localVarAccept != null) localVarRequestOptions.HeaderParameters.Add("Accept", localVarAccept);
+
+            localVarRequestOptions.PathParameters.Add("petId", Org.OpenAPITools.Client.ClientUtils.ParameterToString(petId)); // path parameter
+
+            // authentication (petstore_auth) required
+            // oauth required
+            if (!string.IsNullOrEmpty(this.Configuration.AccessToken) && !localVarRequestOptions.HeaderParameters.ContainsKey("Authorization"))
+            {
+                localVarRequestOptions.HeaderParameters.Add("Authorization", "Bearer " + this.Configuration.AccessToken);
+            }
+
+            // make the HTTP request
+
+            var task = this.AsynchronousClient.PostAsync<ApiResponse>("/pet/{petId}/uploadImages", localVarRequestOptions, this.Configuration, cancellationToken);
+
+#if UNITY_EDITOR || !UNITY_WEBGL
+            var localVarResponse = await task.ConfigureAwait(false);
+#else
+            var localVarResponse = await task;
+#endif
+
+            if (this.ExceptionFactory != null)
+            {
+                Exception _exception = this.ExceptionFactory("UploadFiles", localVarResponse);
+                if (_exception != null) throw _exception;
+            }
+
+            return localVarResponse;
+        }
+
     }
 }