Structured outputs `Map` handling has confusing error message and isn't well documented

I found that when you pass an object with a map to StructuredChatCompletionCreateParams the API returns a 400 response Caused by: com.openai.errors.BadRequestException: 400: Invalid schema for response_format 'json-schema-from-TestMap': In context=(), 'required' is required to be supplied and to be an array including every key in properties. Extra required key 'coolMap' supplied.

Object

  private static class TestMap {
    public Map<String, Integer> coolMap;
  }

Full stack

Caused by: com.openai.errors.BadRequestException: 400: Invalid schema for response_format 'json-schema-from-TestMap': In context=(), 'required' is required to be supplied and to be an array including every key in properties. Extra required key 'coolMap' supplied.
	at com.openai.errors.BadRequestException$Builder.build(BadRequestException.kt:88) ~[openai-java-core-2.0.0.jar:2.0.0]
	at com.openai.core.handlers.ErrorHandler$withErrorHandler$1.handle(ErrorHandler.kt:48) ~[openai-java-core-2.0.0.jar:2.0.0]
	at com.openai.services.blocking.chat.ChatCompletionServiceImpl$WithRawResponseImpl$create$1.invoke(ChatCompletionServiceImpl.kt:122) ~[openai-java-core-2.0.0.jar:2.0.0]
	at com.openai.services.blocking.chat.ChatCompletionServiceImpl$WithRawResponseImpl$create$1.invoke(ChatCompletionServiceImpl.kt:120) ~[openai-java-core-2.0.0.jar:2.0.0]
	at com.openai.core.http.HttpResponseForKt$parseable$1$parsed$2.invoke(HttpResponseFor.kt:14) ~[openai-java-core-2.0.0.jar:2.0.0]
	at kotlin.SynchronizedLazyImpl.getValue(LazyJVM.kt:74) ~[kotlin-stdlib-1.9.24.jar:1.9.24-release-822]
	at com.openai.core.http.HttpResponseForKt$parseable$1.getParsed(HttpResponseFor.kt:14) ~[openai-java-core-2.0.0.jar:2.0.0]
	at com.openai.core.http.HttpResponseForKt$parseable$1.parse(HttpResponseFor.kt:16) ~[openai-java-core-2.0.0.jar:2.0.0]
	at com.openai.services.blocking.chat.ChatCompletionServiceImpl.create(ChatCompletionServiceImpl.kt:56) ~[openai-java-core-2.0.0.jar:2.0.0]
	at com.openai.services.blocking.chat.ChatCompletionService.create(ChatCompletionService.kt:80) ~[openai-java-core-2.0.0.jar:2.0.0]
	at com.openai.services.blocking.chat.ChatCompletionService.create(ChatCompletionService.kt:67) ~[openai-java-core-2.0.0.jar:2.0.0]
	at com.zeroClick.core.chatgpt.ChatGPT.run(ChatGPT.java:108) ~[classes/:na]

Start at StructuredChatCompletionCreateParams and reproduce the 400 response with the TestMap example containing coolMap. Trace the structured-output schema generation and related documentation, then add regression coverage and clarify the supported Map behavior and error message.