Schemas for subclasses not rendered in GraalVM native image builds

[psinghal04]

Describe the bug
When either the request or response payloads are subclasses in a class hierarchy, the generated OpenAPI UI content does not render the schemas for subclasses, when the Spring Boot app is built and run as a native image using Spring Native and GraalVM. The schemas are rendered properly when the same code is run under non-native, JVM mode.

To Reproduce
Steps to reproduce the behavior:

• What version of spring-boot you are using?
  2.5.4

• What modules and versions of springdoc-openapi are you using?
  springdoc-openapi-ui 1.5.10
  springdoc-openapi-security 1.5.10

• What is the actual and the expected result using OpenAPI Description (yml or json)?

  Expected:
  {"content":{"application/json":{"schema":{"oneOf":[{"$ref":"#/components/schemas/ChildA"},{"$ref":"#/components/schemas/ChildB"},{"$ref":"#/components/schemas/ChildC"}]}}},"required":true}

  Actual:
  {"content":{"application/json":{"schema":{},"exampleSetFlag":false}}

• Provide with a sample code (HelloController) or Test that reproduces the problem

    @GetMapping("/children/{childId}")
    @Operation(summary = "Get child by child ID")
    @ApiResponses(value = {
            @ApiResponse(responseCode = "200", description = "Found the child"),
            @ApiResponse(responseCode = "404", description = "Child not found", content = @Content)
    })
    public AbstractChild byChildId(@PathVariable("childId") String childId) {
        return childrenRepo.findFirstByChildId(childId).orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND, "No child found"));
    }

Note: ChildA, ChildB and ChildC are concrete subclasses of AbstractChild

Expected behavior
The behavior should be the same when the code is run in non-native JVM mode, as well as when the code is built and run as native image using GraalVM and Spring Native. Currently, the non-native JVM mode correctly renders the schema for the class hierarchy in the "schema: oneOf" format, whereas the native build does not generate any schema for the subclasses.

Additional context
Spring Boot 2.5.4
Spring API Doc 1.5.10
Spring Native 0.10.3
GraalVM CE 21.2.0 (build 11.0.12+6-jvmci-21.2-b08

[bnasslahsen]

@psinghal04,

I can confirm it's reproducible with v1.5.10.
I have added a fix that you can test using the latest available snapshot v1.5.11-SNAPHOT.

[psinghal04]

@bnasslahsen , I can confirm that the latest v1.5.11-SNAPSHOT fixes the issue I reported. The subclass schema is now generated properly by my native image build. Thanks!