Description
Describe the bug
Hi there. I faced a problem with generating OpenAPI specification using Kotlin.
I have a parameter in the RestController's method annotated with ParameterObject. The type of this parameter is a Kotlin class with companion object which have a non-const members (fields and/or properties). In my case it has read-only property of type java.time.Duration. When I'm accessing an OpenAPI specification via /v3/api-docs endpoint I'm getting a StackOverflowError at line MethodParameterPojoExtractor:113.
Annotating this property with a JvmField annotation nor JvmStatic didn't help.
I did some debug and realized that the MethodParameterPojoExtractor#extractFrom method is falling into recursion with the Duration.ZERO field which is static too.
To Reproduce
I'm using:
Spring 5.2.4.RELEASE
Spring Boot 2.2.5.RELEASE
SpringDoc OpenAPI 1.5.6
Kotlin 1.4.31
There is an example controller with which it can be reproduced:
@Tag(name = "Some API")
@RestController
@RequestMapping("/example")
class ExampleController {
@GetMapping(produces = [MediaType.TEXT_PLAIN])
@Operation(summary = "My awesome operation")
fun test(@ParameterObject request: TestRequest): ResponseEntity<String> {
return ResponseEntity.ok("test")
}
}
class TestRequest(
@field:Parameter(description = "Some parameter")
val param: String
) {
companion object {
val SOME_CONSTANT_DURATION = Duration.ofHours(1L)
}
}
So if you try to access http://localhost:8080/v3/api-docs you will receive HTTP status code 500 and StackOverflowError stack trace in the logs.
Expected behavior
So I think it should be allowed to use such classes as a parameter annotated with ParameterObject.
Maybe it's not needed to collect static fields in the MethodParameterPojoExtractor#allFieldsOf method.