code: public synchronized ClientBuilder newBuilder(String clientName, Collection<JaxRsFeatureGroup> featureGroupsIn) {
          final JaxRsClientConfig jaxRsConfig = configForClient(clientName);
          return newBuilder(clientName, jaxRsConfig, featureGroupsIn);
      }
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.