What might have caused my rest client to send an empty json object while posting an xml byte array to an endpoint accepting *.* ?

[cghislai]

We had a bug for which the root cause appears to be in quarkus, but i wasn't able to pinpoint it. The bug occured since january 24 2025, so it may be caused by an update to quarkus 3.17.7 or 3.17.8, and was reproduced on quarkus 3.18.2.

We have two quarkus services.

One of them (the server) exposed an endpoint defined by an interface that looks like this:

    @POST
    @Path("/{id: [0-9]+}/ubl")
    @Consumes(MediaType.WILDCARD)
    WsCustomerDocument importUblDocument(@PathParam("id") Long customerId,
                                         @NotNull @QueryParam("fileName") String fileName,
                                         @NotNull @HeaderParam("x-requested-with") String uplaodedWith,
                                         @NotNull @RequestBody(required = true) InputStream fileDataInputStream);

This service also produce a rest-client library imported in the client. This library handles authentication, and produce rest client instances using the interface defined above using:

 return org.eclipse.microprofile.rest.client.RestClientBuilder.newBuilder()
                    .baseUrl(clientConfiguration.getApiUri().toURL())
                    .register(new ConfiguredDebugResponseFilter(clientConfiguration))
                    .register(createAuthorizationHeaderFilter())
                    .build(resourceClass);

The client service fetches xml content (as a byte array), and sent it using the endpoint defined above.

The issue was that for some content, the client would send an empty json object {} rather than the xml content as the request body. It was reproducible for specific documents, while most documents would be uploaded fine. There was nothing i could find in the document content though, all were valid xml.

Changing the interface to only accept text/xml rather */* fixed the issue, but im not sure where to report the issue, or whether it is expected behaviour. While debugging i did not manage to find the place where this json conversion was performed.

Does anyone have any tip for debugging this issue?

[quarkus-bot[bot]]

/cc @cescoffier (rest-client), @geoand (rest-client)

[gsmet]

I recommend that you create a simple Maven reproducer for which we can observe the difference between versions.

Given what you describe, I fail to see how we will be able to find out what's going on without a simple reproducer.

Thanks!