RESTEasy reactive passed null media type for MessageBodyWriters

[sithmein]

Describe the bug

Consider the following JAX-RS resource class and MessageBodyWriter:

@Produces(MediaType.APPLICATION_JSON)
@Path("/")
public class MediaTypeLost {
	@Provider
	@Produces(MediaType.APPLICATION_JSON)
	public static class GenericJSONSerializer implements MessageBodyWriter<Object> {
	    @Override
	    public long getSize(final Object value, final Class<?> type, final Type genericType,
	        final Annotation [] annotations, final MediaType mediaType) {
	        return -1;
	    }

	    @Override
	    public boolean isWriteable(final Class<?> type, final Type genericType, final Annotation [] annotations,
	        final MediaType mediaType) {
	        return true;
	    }

	    @Override
	    public void writeTo(final Object value, final Class<?> type, final Type genericType,
	        final Annotation[] annotations, final MediaType mediaType,
	        final MultivaluedMap<String, Object> httpHeaders, final OutputStream entityStream)
	        throws IOException {
	        
	    	Objects.requireNonNull(mediaType);
	    }
	}

	
    @GET
    @Path("foo")
	public Response doSomething() {
    	var map = Map.of("key", "value");
	    return Response.ok(map).build();
	}
}

Invoking the resource method with quarkus-resteasy-reactive will result in an exception because the mediaType parameter passed into the message body writer is null. This works without problems in the non-reactive version and any other JAX-RS framework that I have used in the past.
It works if the Response explicitly defines its media type it works, but according to section 3.8 of the JAX-RS specification this is not necessary and the media type can be derived from @Produces annotations.

Expected behavior

The message body writer should receive the correct media type (application/json in this case), according to the JAX-RS specification.

Actual behavior

The media type is null.

How to Reproduce?

Run the provided example with reactive RESTEasy.

Output of uname -a or ver

No response

Output of java -version

17

GraalVM version (if different from Java)

No response

Quarkus version or git rev

2.8.2.Final

Build tool (ie. output of mvnw --version or gradlew --version)

No response

Additional information

No response

[quarkus-bot]

/cc @FroMage, @geoand, @stuartwdouglas

[geoand]

Thanks for reporting.

Do you mind attaching a sample project that exhibits this behavior?

[sithmein]

You can find reproducers/tests for this issue at https://github.com/sithmein/bugs-in-quarkus

[geoand]

I'm surprised that none of the TCK tests actually tested this...

In any case, #25291 fixes the null media type issue.
Please open a new issue if there is another problem (as indicated by the other test in your repo)