code: public synchronized ClientBuilder newBuilder(String clientName, JaxRsFeatureGroup feature, JaxRsFeatureGroup... moreFeatures) {
          return newBuilder(clientName, ImmutableList.<JaxRsFeatureGroup>builder()
                  .add(feature)
                  .addAll(Arrays.asList(moreFeatures))
                  .build());
      }
docs: Create a new {@link ClientBuilder} instance with the given name and groups.
  You own the returned client and are responsible for managing its cleanup.