One way to send specific HTTP (error) status codes from a JAX-RS resource is to use the javax.ws.rs.core.Response class with its Builder Pattern-like API. If you want to specify the return type according to the response body, you can still do so and send a different status on errors by throwing a WebApplicationException.

@Path("test")
public class TestResource {

 @GET
 public String hello() {
 if (new Random().nextBoolean())
 throw new WebApplicationException(Response.Status.CONFLICT);

 return "Hello World, " + Instant.now();
 }

}

The constructors of this special type of exception accepts Responses, Response.Statuses or int types. The JAX-RS runtime will send the corresponding HTTP statuses and header fields, respectively.

There are also pre-defined subtypes of WebApplicationException for common errors like NotFoundException or BadRequestException.