OpenAPI model not considering mixins in natibe build

[ivivanov-bg]

Bug description

When using camel-quarkus-openapi-java generation of the OpenAPI specification in native mode doesn't take into account the mixins specified in the swagger-core library:

https://github.com/swagger-api/swagger-core/blob/3fcc473c33c56f306902853a451020926ad691ea/modules/swagger-core/src/main/java/io/swagger/v3/core/util/ObjectMapperFactory.java#L244

In JVM mode - everything works as expected.

The root cause of the issue is that the mixins are abstract classes without any children, so they get stripped during native build.
As a result - the OpenAPI document might become very big (in case of complex data model) and make swagger UI completely unresponsive.

The extension should register the mixins for reflection to prevent flooding openapi json with unnecessary data.

Attached is sample reproduces: [sample-app.zip](https://github.com/apache/camel-quarkus/files/14634597/sample-app.zip)

In JVM mode openapi size (accessible on /v1/openapi) is 1502 bytes
In Native mode openapi size (accessible on /v1/openapi) is 3653 bytes
(The difference comes mostly from Components -> Schemas -> <DataType> -> jsonSchema section)

[zhfeng]

Thanks @ivivanov-bg - I will take a look.

[zhfeng]

@ivivanov-bg what the mixin classes should be registered for reflection? I tried all class from io.swagger.v3.core.jackson.mixin but the native runner is producing an empty response now.

[ivivanov-bg]

That's exacrly what I observed too and the reason to not privide a PR directly.

My cussrent issue (with the jsonSchema) gets resolved if the Schema31 mixin and the inner type serializer are registered, but to me this looked more like a workaround for particular situation

[zhfeng]

io.swagger.v3.core.jackson.mixin.Schema31Mixin and Schema31Mixin.TypeSerializer ?

[ivivanov-bg]

Yes
Attached is updated sample-app
sample-app.zip

But again - this only fixes my problem (and only partially)
I think all those mixins needs to be analyzed and decide how to proceed in native mode.

[zhfeng]

Thanks @ivivanov-bg - yeah, it works by adding all the mixin classes and relavant JsonSerializer. I will prepare a PR with an integration test.

[zhfeng]

@ivivanov-bg can you check the fix with your reproducer? If it works, I will merge the PR.

[ivivanov-bg]

I just tested it - it's working as expected now
Thanks