fix: support import module in removeUnusedImports (GJF 1.30.0)

CHANGES.md

@@ -10,6 +10,11 @@ This document is intended for Spotless developers.
 We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (starting after version `1.27.0`).
 
 ## [Unreleased]
+### Fixed
+- `removeUnusedImports` no longer throws on Java `import module` declarations (`JCModuleImport` ClassCastException). ([#2890](https://github.com/diffplug/spotless/issues/2890))
+### Changes
+- Bump default `google-java-format` version `1.28.0` -> `1.30.0` (first release with `import module` support); require at least `1.30.0` on JVM 25+.
+
 
 ## [4.9.0] - 2026-07-27
 ### Added

gradle/libs.versions.toml

@@ -48,7 +48,7 @@ diktat-rules = "org.cqfn.diktat:diktat-rules:1.2.5"
 diktat-runner = "com.saveourtool.diktat:diktat-runner:2.0.0"
 flexmark-all = "com.vladsch.flexmark:flexmark-all:0.64.8"
 gherkin-utils = "io.cucumber:gherkin-utils:10.0.0"
-google-java-format = "com.google.googlejavaformat:google-java-format:1.28.0"
+google-java-format = "com.google.googlejavaformat:google-java-format:1.30.0"
 gson = "com.google.code.gson:gson:2.14.0"
 javaparser-symbol-solver-core = "com.github.javaparser:javaparser-symbol-solver-core:3.27.1"
 ktfmt = "com.facebook:ktfmt:0.63"

lib/src/main/java/com/diffplug/spotless/java/GoogleJavaFormatStep.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2025 DiffPlug
+ * Copyright 2016-2026 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -121,7 +121,8 @@ private static FormatterStep createInternally(String name, String groupArtifact,
 
 	private static final Jvm.Support<String> JVM_SUPPORT = Jvm.<String> support(NAME)
 			.addMin(21, "1.17.0") // java 21 requires at least 1.17.0 due to https://github.com/google/google-java-format/issues/898
-			.add(17, "1.28.0"); // default version
+			.addMin(25, "1.30.0") // import module (JEP 511) requires google-java-format >= 1.30.0 (https://github.com/google/google-java-format/issues/1213)
+			.add(17, "1.30.0"); // default version (1.30.0+ handles `import module` in RemoveUnusedImports)
 
 	public static String defaultGroupArtifact() {
 		return MAVEN_COORDINATE;

plugin-gradle/CHANGES.md

@@ -3,6 +3,11 @@
 We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (starting after version `3.27.0`).
 
 ## [Unreleased]
+### Fixed
+- `removeUnusedImports` no longer fails on Java `import module` declarations. ([#2890](https://github.com/diffplug/spotless/issues/2890))
+### Changes
+- Bump default `google-java-format` version `1.28.0` -> `1.30.0` (first release with `import module` support); require at least `1.30.0` on JVM 25+.
+
 
 ## [8.9.0] - 2026-07-27
 ### Added

plugin-maven/CHANGES.md

@@ -3,6 +3,11 @@
 We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (starting after version `1.27.0`).
 
 ## [Unreleased]
+### Fixed
+- `removeUnusedImports` no longer fails on Java `import module` declarations. ([#2890](https://github.com/diffplug/spotless/issues/2890))
+### Changes
+- Bump default `google-java-format` version `1.28.0` -> `1.30.0` (first release with `import module` support); require at least `1.30.0` on JVM 25+.
+
 
 ## [3.9.0] - 2026-07-27
 ### Added

testlib/src/main/resources/java/removeunusedimports/ModuleImportFormatted.test

@@ -0,0 +1,10 @@
+import module java.base;
+import java.util.ArrayList;
+import java.util.List;
+
+class ModuleImportTest {
+	void test() {
+		UUID.randomUUID();
+		List<String> list = new ArrayList<>();
+	}
+}

testlib/src/main/resources/java/removeunusedimports/ModuleImportUnformatted.test

@@ -0,0 +1,10 @@
+import module java.base;
+import java.util.ArrayList;
+import java.util.List;
+
+class ModuleImportTest {
+	void test() {
+		UUID.randomUUID();
+		List<String> list = new ArrayList<>();
+	}
+}

testlib/src/main/resources/java/removeunusedimports/ModuleImportWithUnusedFormatted.test

@@ -0,0 +1,10 @@
+import module java.base;
+import java.util.ArrayList;
+import java.util.List;
+
+class ModuleImportWithUnused {
+	void test() {
+		UUID.randomUUID();
+		List<String> list = new ArrayList<>();
+	}
+}

testlib/src/main/resources/java/removeunusedimports/ModuleImportWithUnusedUnformatted.test

@@ -0,0 +1,11 @@
+import module java.base;
+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.List;
+
+class ModuleImportWithUnused {
+	void test() {
+		UUID.randomUUID();
+		List<String> list = new ArrayList<>();
+	}
+}

testlib/src/test/java/com/diffplug/spotless/java/GoogleJavaFormatStepTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2025 DiffPlug
+ * Copyright 2016-2026 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,6 +17,7 @@
 
 import static org.junit.jupiter.api.condition.JRE.JAVA_20;
 import static org.junit.jupiter.api.condition.JRE.JAVA_21;
+import static org.junit.jupiter.api.condition.JRE.JAVA_25;
 
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.condition.EnabledForJreRange;
@@ -75,6 +76,16 @@ void versionBelowOneDotTenIsNotAllowed() throws Exception {
 				.toBe("LINE_UNDEFINED google-java-format(jvm-version) You are running Spotless on JVM 21. This requires google-java-format of at least 1.17.0 (you are using 1.9). (...)");
 	}
 
+
+	@Test
+	@EnabledForJreRange(min = JAVA_25)
+	void versionBelowMinOnJava25IsNotAllowed() throws Exception {
+		FormatterStep step = GoogleJavaFormatStep.create("1.28.0", "AOSP", TestProvisioner.mavenCentral());
+		StepHarness.forStepNoRoundtrip(step)
+				.expectLintsOfResource("java/googlejavaformat/JavaCodeWithLicenseUnformatted.test")
+				.toBe("LINE_UNDEFINED google-java-format(jvm-version) You are running Spotless on JVM 25. This requires google-java-format of at least 1.30.0 (you are using 1.28.0). (...)");
+	}
+
 	@Test
 	void behaviorWithAospStyle() throws Exception {
 		FormatterStep step = GoogleJavaFormatStep.create(GoogleJavaFormatStep.defaultVersion(), "AOSP", TestProvisioner.mavenCentral());

testlib/src/test/java/com/diffplug/spotless/java/RemoveUnusedImportsStep_withGoogleJavaFormatTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2025 DiffPlug
+ * Copyright 2016-2026 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,6 +16,8 @@
 package com.diffplug.spotless.java;
 
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.condition.EnabledForJreRange;
+import org.junit.jupiter.api.condition.JRE;
 
 import com.diffplug.spotless.FormatterStep;
 import com.diffplug.spotless.SerializableEqualityTester;
@@ -38,6 +40,20 @@ void behavior() throws Exception {
 		;
 	}
 
+	/**
+	 * {@code import module} (JEP 511) is only parseable on JDK 25+. google-java-format 1.30+
+	 * skips module imports in {@code RemoveUnusedImports} instead of ClassCastException on
+	 * {@code JCModuleImport} (https://github.com/diffplug/spotless/issues/2890).
+	 */
+	@Test
+	@EnabledForJreRange(min = JRE.JAVA_25)
+	void moduleImports() throws Exception {
+		FormatterStep step = RemoveUnusedImportsStep.create(RemoveUnusedImportsStep.GJF, TestProvisioner.mavenCentral());
+		StepHarness.forStep(step)
+				.testResource("java/removeunusedimports/ModuleImportUnformatted.test", "java/removeunusedimports/ModuleImportFormatted.test")
+				.testResource("java/removeunusedimports/ModuleImportWithUnusedUnformatted.test", "java/removeunusedimports/ModuleImportWithUnusedFormatted.test");
+	}
+
 	@Test
 	void equality() throws Exception {
 		new SerializableEqualityTester() {