code: public WellRestedRequestBuilder globalHeaders(Map<String, String> globalHeaders) {
          this.globalHeaders = WellRestedUtil.buildHeaders(globalHeaders);
          return this;
      }
docs: Use this method to add some global headers to the WellRestedRequest object.
  These headers are going to be added on every request you make. <br/>
  A good use for this method is setting a global authentication header or a content type header.