fix(mdx-web): restore default message converters

[stevecl5]

Summary of Changes

Resolves an issue introduced during the Spring Boot 4 upgrade where default HTTP message converters (like ByteArrayHttpMessageConverter and StringHttpMessageConverter) were dropped, causing endpoints like /actuator/prometheus to return a 500 Internal Server Error.

Root Cause:
In Spring Boot 4, overriding configureMessageConverters signals to the framework that the application is taking complete manual control of serialization which causes Spring to discard all of its default converters. A new GsonHttpMessageConverter was added back in MdxSerializationConfiguration to fix JSON serialization, but endpoints that return other media types (such as text/plain) were missing the necessary converters to render a response.

The Fix:

• Migrated MdxOnDemandSerializationWebMvcConfigurer to use extendMessageConverters instead of configureMessageConverters. This allows Spring Boot to safely populate its default converters first, which we then filter to our strict whitelist.
• Cleaned up MdxSerializationConfiguration by removing the WebMvcConfigurer implementation. Spring Boot will automatically detect our custom @Bean Gson gson() and natively bind it to its own default Gson converter under the hood.

Fixes # https://mxcom.atlassian.net/browse/MC-15146

Public API Additions/Changes

N/A

Downstream Consumer Impact

• Spring Boot services utilizing this library will regain access to standard default converters.
• Spring Boot services will be able to query prometheus metrics without getting an error, as long as the endpoint is enabled in the Spring configuration ( application.yml or application.properties ).
• No breaking changes to existing JSON or XML serialization.

How Has This Been Tested?

I pulled a snapshot version of these changes into path-connector-hancock-whitney and verified the /actuator/prometheus endpoint is working as expected.

Prometheus Response

% curl -s http://localhost:13024/actuator/prometheus 
# HELP application_ready_time_seconds Time taken for the application to be ready to service requests
# TYPE application_ready_time_seconds gauge
application_ready_time_seconds{application="path-connector-hancock-whitney",main_application_class="hancockwhitney.HancockWhitneyApplication"} 226.071
# HELP application_started_time_seconds Time taken to start the application
# TYPE application_started_time_seconds gauge
application_started_time_seconds{application="path-connector-hancock-whitney",main_application_class="hancockwhitney.HancockWhitneyApplication"} 226.053
# HELP disk_free_bytes Usable space for path
# TYPE disk_free_bytes gauge
disk_free_bytes{application="path-connector-hancock-whitney",path="/Users/steven.leighton/dev/path-connector-hancock-whitney/."} 6.2999728128E10
# HELP disk_total_bytes Total space for path
# TYPE disk_total_bytes gauge
disk_total_bytes{application="path-connector-hancock-whitney",path="/Users/steven.leighton/dev/path-connector-hancock-whitney/."} 4.94384795648E11
# HELP executor_active_threads The approximate number of threads that are actively executing tasks
# TYPE executor_active_threads gauge
executor_active_threads{application="path-connector-hancock-whitney",name="applicationTaskExecutor"} 0.0
# HELP executor_completed_tasks_total The approximate total number of tasks that have completed execution
# TYPE executor_completed_tasks_total counter
executor_completed_tasks_total{application="path-connector-hancock-whitney",name="applicationTaskExecutor"} 0.0
# HELP executor_pool_core_threads The core number of threads for the pool
# TYPE executor_pool_core_threads gauge
executor_pool_core_threads{application="path-connector-hancock-whitney",name="applicationTaskExecutor"} 8.0
# HELP executor_pool_max_threads The maximum allowed number of threads in the pool
# TYPE executor_pool_max_threads gauge
executor_pool_max_threads{application="path-connector-hancock-whitney",name="applicationTaskExecutor"} 2.147483647E9
# HELP executor_pool_size_threads The current number of threads in the pool
# TYPE executor_pool_size_threads gauge
executor_pool_size_threads{application="path-connector-hancock-whitney",name="applicationTaskExecutor"} 0.0
# HELP executor_queue_remaining_tasks The number of additional elements that this queue can ideally accept without blocking
# TYPE executor_queue_remaining_tasks gauge
executor_queue_remaining_tasks{application="path-connector-hancock-whitney",name="applicationTaskExecutor"} 2.147483647E9
# HELP executor_queued_tasks The approximate number of tasks that are queued for execution
# TYPE executor_queued_tasks gauge
executor_queued_tasks{application="path-connector-hancock-whitney",name="applicationTaskExecutor"} 0.0
# HELP http_server_requests_active_seconds  
# TYPE http_server_requests_active_seconds summary
http_server_requests_active_seconds_count{application="path-connector-hancock-whitney",exception="none",method="GET",outcome="SUCCESS",status="200",uri="UNKNOWN"} 1
http_server_requests_active_seconds_sum{application="path-connector-hancock-whitney",exception="none",method="GET",outcome="SUCCESS",status="200",uri="UNKNOWN"} 0.002270292
# HELP http_server_requests_active_seconds_max  
# TYPE http_server_requests_active_seconds_max gauge
http_server_requests_active_seconds_max{application="path-connector-hancock-whitney",exception="none",method="GET",outcome="SUCCESS",status="200",uri="UNKNOWN"} 0.002277709
# HELP http_server_requests_seconds  
# TYPE http_server_requests_seconds summary
http_server_requests_seconds_count{application="path-connector-hancock-whitney",error="none",exception="none",method="GET",outcome="CLIENT_ERROR",status="404",uri="/**"} 1
http_server_requests_seconds_sum{application="path-connector-hancock-whitney",error="none",exception="none",method="GET",outcome="CLIENT_ERROR",status="404",uri="/**"} 0.018238
http_server_requests_seconds_count{application="path-connector-hancock-whitney",error="none",exception="none",method="GET",outcome="SUCCESS",status="200",uri="/actuator/prometheus"} 2
http_server_requests_seconds_sum{application="path-connector-hancock-whitney",error="none",exception="none",method="GET",outcome="SUCCESS",status="200",uri="/actuator/prometheus"} 0.2791595
# HELP http_server_requests_seconds_max  
# TYPE http_server_requests_seconds_max gauge
http_server_requests_seconds_max{application="path-connector-hancock-whitney",error="none",exception="none",method="GET",outcome="CLIENT_ERROR",status="404",uri="/**"} 0.018238
http_server_requests_seconds_max{application="path-connector-hancock-whitney",error="none",exception="none",method="GET",outcome="SUCCESS",status="200",uri="/actuator/prometheus"} 0.218872375
# HELP jvm_info JVM version info
# TYPE jvm_info gauge
jvm_info{application="path-connector-hancock-whitney",runtime="OpenJDK Runtime Environment",vendor="Eclipse Adoptium",version="21.0.10+7-LTS"} 1
# HELP jvm_buffer_count_buffers An estimate of the number of buffers in the pool
# TYPE jvm_buffer_count_buffers gauge
jvm_buffer_count_buffers{application="path-connector-hancock-whitney",id="direct"} 10.0
jvm_buffer_count_buffers{application="path-connector-hancock-whitney",id="mapped"} 0.0
jvm_buffer_count_buffers{application="path-connector-hancock-whitney",id="mapped - 'non-volatile memory'"} 0.0
# HELP jvm_buffer_memory_used_bytes An estimate of the memory that the Java virtual machine is using for this buffer pool
# TYPE jvm_buffer_memory_used_bytes gauge
jvm_buffer_memory_used_bytes{application="path-connector-hancock-whitney",id="direct"} 81920.0
jvm_buffer_memory_used_bytes{application="path-connector-hancock-whitney",id="mapped"} 0.0
jvm_buffer_memory_used_bytes{application="path-connector-hancock-whitney",id="mapped - 'non-volatile memory'"} 0.0
# HELP jvm_buffer_total_capacity_bytes An estimate of the total capacity of the buffers in this pool
# TYPE jvm_buffer_total_capacity_bytes gauge
jvm_buffer_total_capacity_bytes{application="path-connector-hancock-whitney",id="direct"} 81920.0
jvm_buffer_total_capacity_bytes{application="path-connector-hancock-whitney",id="mapped"} 0.0
jvm_buffer_total_capacity_bytes{application="path-connector-hancock-whitney",id="mapped - 'non-volatile memory'"} 0.0
# HELP jvm_classes_loaded_classes The number of classes that are currently loaded in the Java virtual machine
# TYPE jvm_classes_loaded_classes gauge
jvm_classes_loaded_classes{application="path-connector-hancock-whitney"} 14007.0
# HELP jvm_classes_loaded_count_classes_total The number of classes loaded in the Java virtual machine
# TYPE jvm_classes_loaded_count_classes_total counter
jvm_classes_loaded_count_classes_total{application="path-connector-hancock-whitney"} 14007.0
# HELP jvm_classes_unloaded_classes_total The number of classes unloaded in the Java virtual machine
# TYPE jvm_classes_unloaded_classes_total counter
jvm_classes_unloaded_classes_total{application="path-connector-hancock-whitney"} 0.0
# HELP jvm_compilation_time_ms_total The approximate accumulated elapsed time spent in compilation
# TYPE jvm_compilation_time_ms_total counter
jvm_compilation_time_ms_total{application="path-connector-hancock-whitney",compiler="HotSpot 64-Bit Tiered Compilers"} 2013.0
# HELP jvm_gc_live_data_size_bytes Size of long-lived heap memory pool after reclamation
# TYPE jvm_gc_live_data_size_bytes gauge
jvm_gc_live_data_size_bytes{application="path-connector-hancock-whitney"} 0.0
# HELP jvm_gc_max_data_size_bytes Max size of long-lived heap memory pool
# TYPE jvm_gc_max_data_size_bytes gauge
jvm_gc_max_data_size_bytes{application="path-connector-hancock-whitney"} 8.589934592E9
# HELP jvm_gc_memory_allocated_bytes_total Incremented for an increase in the size of the (young) heap memory pool after one GC to before the next
# TYPE jvm_gc_memory_allocated_bytes_total counter
jvm_gc_memory_allocated_bytes_total{application="path-connector-hancock-whitney"} 7.5497472E7
# HELP jvm_gc_memory_promoted_bytes_total Count of positive increases in the size of the old generation memory pool before GC to after GC
# TYPE jvm_gc_memory_promoted_bytes_total counter
jvm_gc_memory_promoted_bytes_total{application="path-connector-hancock-whitney"} 775248.0
# HELP jvm_gc_overhead An approximation of the percent of CPU time used by GC activities over the last lookback period or since monitoring began, whichever is shorter, in the range [0..1]
# TYPE jvm_gc_overhead gauge
jvm_gc_overhead{application="path-connector-hancock-whitney"} 1.889260178899562E-4
# HELP jvm_gc_pause_seconds Time spent in GC pause
# TYPE jvm_gc_pause_seconds summary
jvm_gc_pause_seconds_count{action="end of minor GC",application="path-connector-hancock-whitney",cause="G1 Evacuation Pause",gc="G1 Young Generation"} 1
jvm_gc_pause_seconds_sum{action="end of minor GC",application="path-connector-hancock-whitney",cause="G1 Evacuation Pause",gc="G1 Young Generation"} 0.012
# HELP jvm_gc_pause_seconds_max Time spent in GC pause
# TYPE jvm_gc_pause_seconds_max gauge
jvm_gc_pause_seconds_max{action="end of minor GC",application="path-connector-hancock-whitney",cause="G1 Evacuation Pause",gc="G1 Young Generation"} 0.012
# HELP jvm_memory_committed_bytes The amount of memory in bytes that is committed for the Java virtual machine to use
# TYPE jvm_memory_committed_bytes gauge
jvm_memory_committed_bytes{application="path-connector-hancock-whitney",area="heap",id="G1 Eden Space"} 7.5497472E7
jvm_memory_committed_bytes{application="path-connector-hancock-whitney",area="heap",id="G1 Old Gen"} 5.4525952E7
jvm_memory_committed_bytes{application="path-connector-hancock-whitney",area="heap",id="G1 Survivor Space"} 1.2582912E7
jvm_memory_committed_bytes{application="path-connector-hancock-whitney",area="nonheap",id="CodeCache"} 1.5138816E7
jvm_memory_committed_bytes{application="path-connector-hancock-whitney",area="nonheap",id="Compressed Class Space"} 9961472.0
jvm_memory_committed_bytes{application="path-connector-hancock-whitney",area="nonheap",id="Metaspace"} 7.5235328E7
# HELP jvm_memory_max_bytes The maximum amount of memory in bytes that can be used for memory management
# TYPE jvm_memory_max_bytes gauge
jvm_memory_max_bytes{application="path-connector-hancock-whitney",area="heap",id="G1 Eden Space"} -1.0
jvm_memory_max_bytes{application="path-connector-hancock-whitney",area="heap",id="G1 Old Gen"} 8.589934592E9
jvm_memory_max_bytes{application="path-connector-hancock-whitney",area="heap",id="G1 Survivor Space"} -1.0
jvm_memory_max_bytes{application="path-connector-hancock-whitney",area="nonheap",id="CodeCache"} 5.0331648E7
jvm_memory_max_bytes{application="path-connector-hancock-whitney",area="nonheap",id="Compressed Class Space"} 1.073741824E9
jvm_memory_max_bytes{application="path-connector-hancock-whitney",area="nonheap",id="Metaspace"} -1.0
# HELP jvm_memory_usage_after_gc The percentage of long-lived heap pool used after the last GC event, in the range [0..1]
# TYPE jvm_memory_usage_after_gc gauge
jvm_memory_usage_after_gc{application="path-connector-hancock-whitney",area="heap",pool="long-lived"} 0.004819517955183983
# HELP jvm_memory_used_bytes The amount of used memory
# TYPE jvm_memory_used_bytes gauge
jvm_memory_used_bytes{application="path-connector-hancock-whitney",area="heap",id="G1 Eden Space"} 2.9360128E7
jvm_memory_used_bytes{application="path-connector-hancock-whitney",area="heap",id="G1 Old Gen"} 4.1399344E7
jvm_memory_used_bytes{application="path-connector-hancock-whitney",area="heap",id="G1 Survivor Space"} 8581280.0
jvm_memory_used_bytes{application="path-connector-hancock-whitney",area="nonheap",id="CodeCache"} 1.5068928E7
jvm_memory_used_bytes{application="path-connector-hancock-whitney",area="nonheap",id="Compressed Class Space"} 9554552.0
jvm_memory_used_bytes{application="path-connector-hancock-whitney",area="nonheap",id="Metaspace"} 7.4285688E7
# HELP jvm_threads_daemon_threads The current number of live daemon threads
# TYPE jvm_threads_daemon_threads gauge
jvm_threads_daemon_threads{application="path-connector-hancock-whitney"} 28.0
# HELP jvm_threads_live_threads The current number of live threads including both daemon and non-daemon threads
# TYPE jvm_threads_live_threads gauge
jvm_threads_live_threads{application="path-connector-hancock-whitney"} 32.0
# HELP jvm_threads_peak_threads The peak live thread count since the Java virtual machine started or peak was reset
# TYPE jvm_threads_peak_threads gauge
jvm_threads_peak_threads{application="path-connector-hancock-whitney"} 36.0
# HELP jvm_threads_started_threads_total The total number of application threads started in the JVM
# TYPE jvm_threads_started_threads_total counter
jvm_threads_started_threads_total{application="path-connector-hancock-whitney"} 67.0
# HELP jvm_threads_states_threads The current number of threads
# TYPE jvm_threads_states_threads gauge
jvm_threads_states_threads{application="path-connector-hancock-whitney",state="blocked"} 0.0
jvm_threads_states_threads{application="path-connector-hancock-whitney",state="new"} 0.0
jvm_threads_states_threads{application="path-connector-hancock-whitney",state="runnable"} 9.0
jvm_threads_states_threads{application="path-connector-hancock-whitney",state="terminated"} 0.0
jvm_threads_states_threads{application="path-connector-hancock-whitney",state="timed-waiting"} 11.0
jvm_threads_states_threads{application="path-connector-hancock-whitney",state="waiting"} 12.0
# HELP logback_events_total Number of log events that were enabled by the effective log level
# TYPE logback_events_total counter
logback_events_total{application="path-connector-hancock-whitney",level="debug"} 0.0
logback_events_total{application="path-connector-hancock-whitney",level="error"} 0.0
logback_events_total{application="path-connector-hancock-whitney",level="info"} 9.0
logback_events_total{application="path-connector-hancock-whitney",level="trace"} 0.0
logback_events_total{application="path-connector-hancock-whitney",level="warn"} 0.0
# HELP process_cpu_time_ns_total The "cpu time" used by the Java Virtual Machine process
# TYPE process_cpu_time_ns_total counter
process_cpu_time_ns_total{application="path-connector-hancock-whitney"} 2.24719E10
# HELP process_cpu_usage The "recent cpu usage" for the Java Virtual Machine process
# TYPE process_cpu_usage gauge
process_cpu_usage{application="path-connector-hancock-whitney"} 0.0064926474464930386
# HELP process_files_max_files The maximum file descriptor count
# TYPE process_files_max_files gauge
process_files_max_files{application="path-connector-hancock-whitney"} 1048576.0
# HELP process_files_open_files The open file descriptor count
# TYPE process_files_open_files gauge
process_files_open_files{application="path-connector-hancock-whitney"} 183.0
# HELP process_start_time_seconds Start time of the process since unix epoch.
# TYPE process_start_time_seconds gauge
process_start_time_seconds{application="path-connector-hancock-whitney"} 1.786681036208E9
# HELP process_uptime_seconds The uptime of the Java virtual machine
# TYPE process_uptime_seconds gauge
process_uptime_seconds{application="path-connector-hancock-whitney"} 292.291
# HELP system_cpu_count The number of processors available to the Java virtual machine
# TYPE system_cpu_count gauge
system_cpu_count{application="path-connector-hancock-whitney"} 8.0
# HELP system_cpu_usage The "recent cpu usage" of the system the application is running in
# TYPE system_cpu_usage gauge
system_cpu_usage{application="path-connector-hancock-whitney"} 0.20074349442379183
# HELP system_load_average_1m The sum of the number of runnable entities queued to available processors and the number of runnable entities running on the available processors averaged over a period of time
# TYPE system_load_average_1m gauge
system_load_average_1m{application="path-connector-hancock-whitney"} 15.46630859375
# HELP tomcat_cache_access_total  
# TYPE tomcat_cache_access_total counter
tomcat_cache_access_total{application="path-connector-hancock-whitney"} 0.0
# HELP tomcat_cache_hit_total  
# TYPE tomcat_cache_hit_total counter
tomcat_cache_hit_total{application="path-connector-hancock-whitney"} 0.0
# HELP tomcat_connections_config_max_connections  
# TYPE tomcat_connections_config_max_connections gauge
tomcat_connections_config_max_connections{application="path-connector-hancock-whitney",name="http-nio-13024"} 8192.0
# HELP tomcat_connections_current_connections  
# TYPE tomcat_connections_current_connections gauge
tomcat_connections_current_connections{application="path-connector-hancock-whitney",name="http-nio-13024"} 2.0
# HELP tomcat_connections_keepalive_current_connections  
# TYPE tomcat_connections_keepalive_current_connections gauge
tomcat_connections_keepalive_current_connections{application="path-connector-hancock-whitney",name="http-nio-13024"} 1.0
# HELP tomcat_global_error_total  
# TYPE tomcat_global_error_total counter
tomcat_global_error_total{application="path-connector-hancock-whitney",name="http-nio-13024"} 1.0
# HELP tomcat_global_received_bytes_total  
# TYPE tomcat_global_received_bytes_total counter
tomcat_global_received_bytes_total{application="path-connector-hancock-whitney",name="http-nio-13024"} 0.0
# HELP tomcat_global_request_max_seconds  
# TYPE tomcat_global_request_max_seconds gauge
tomcat_global_request_max_seconds{application="path-connector-hancock-whitney",name="http-nio-13024"} 0.257
# HELP tomcat_global_request_seconds  
# TYPE tomcat_global_request_seconds summary
tomcat_global_request_seconds_count{application="path-connector-hancock-whitney",name="http-nio-13024"} 3
tomcat_global_request_seconds_sum{application="path-connector-hancock-whitney",name="http-nio-13024"} 0.362
# HELP tomcat_global_sent_bytes_total  
# TYPE tomcat_global_sent_bytes_total counter
tomcat_global_sent_bytes_total{application="path-connector-hancock-whitney",name="http-nio-13024"} 39258.0
# HELP tomcat_servlet_error_total  
# TYPE tomcat_servlet_error_total counter
tomcat_servlet_error_total{application="path-connector-hancock-whitney",name="dispatcherServlet"} 1.0
# HELP tomcat_servlet_request_max_seconds  
# TYPE tomcat_servlet_request_max_seconds gauge
tomcat_servlet_request_max_seconds{application="path-connector-hancock-whitney",name="dispatcherServlet"} 0.236
# HELP tomcat_servlet_request_seconds  
# TYPE tomcat_servlet_request_seconds summary
tomcat_servlet_request_seconds_count{application="path-connector-hancock-whitney",name="dispatcherServlet"} 4
tomcat_servlet_request_seconds_sum{application="path-connector-hancock-whitney",name="dispatcherServlet"} 0.315
# HELP tomcat_sessions_active_current_sessions  
# TYPE tomcat_sessions_active_current_sessions gauge
tomcat_sessions_active_current_sessions{application="path-connector-hancock-whitney"} 0.0
# HELP tomcat_sessions_active_max_sessions  
# TYPE tomcat_sessions_active_max_sessions gauge
tomcat_sessions_active_max_sessions{application="path-connector-hancock-whitney"} 0.0
# HELP tomcat_sessions_alive_max_seconds  
# TYPE tomcat_sessions_alive_max_seconds gauge
tomcat_sessions_alive_max_seconds{application="path-connector-hancock-whitney"} 0.0
# HELP tomcat_sessions_created_sessions_total  
# TYPE tomcat_sessions_created_sessions_total counter
tomcat_sessions_created_sessions_total{application="path-connector-hancock-whitney"} 0.0
# HELP tomcat_sessions_expired_sessions_total  
# TYPE tomcat_sessions_expired_sessions_total counter
tomcat_sessions_expired_sessions_total{application="path-connector-hancock-whitney"} 0.0
# HELP tomcat_sessions_rejected_sessions_total  
# TYPE tomcat_sessions_rejected_sessions_total counter
tomcat_sessions_rejected_sessions_total{application="path-connector-hancock-whitney"} 0.0
# HELP tomcat_threads_busy_threads  
# TYPE tomcat_threads_busy_threads gauge
tomcat_threads_busy_threads{application="path-connector-hancock-whitney",name="http-nio-13024"} 1.0
# HELP tomcat_threads_config_max_threads  
# TYPE tomcat_threads_config_max_threads gauge
tomcat_threads_config_max_threads{application="path-connector-hancock-whitney",name="http-nio-13024"} 200.0
# HELP tomcat_threads_current_threads  
# TYPE tomcat_threads_current_threads gauge
tomcat_threads_current_threads{application="path-connector-hancock-whitney",name="http-nio-13024"} 10.0

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works