private void handleProducesAnnotation(Produces produces, MethodMetadata data) {
    final String[] serverProduces =
        removeValues(produces.value(), mediaType -> emptyToNull(mediaType) == null, String.class);
    checkState(serverProduces.length > 0, "Produces.value() was empty on %s", data.configKey());
    data.template().header(ACCEPT, Collections.emptyList()); // remove any previous produces
    data.template().header(ACCEPT, serverProduces);
  }
Please refer to the <a href="https://github.com/Netflix/feign/tree/master/feign-jaxrs">Feign
JAX-RS README</a>.
jaxrs/src/main/java/feign/jaxrs/JAXRSContract.java