code: public R addRepresentationHintGroup(String... hints) {
          if(hints != null) {
              mHintHeader.append("[");
              mHintHeader.append(TextUtils.join(",", hints));
              mHintHeader.append("]");
          }
          return (R) this;
      }
docs: Include a representation hint group into this request.
  Please refer to representation documentation for more details
  @param hints string list with all the representation hints
  @return request with updated hint group