code: public WellRestedRequestBuilder addGlobalHeader(String name, String value) {
          if (this.globalHeaders == null) {
              this.globalHeaders = new ArrayList<>();
          }
          this.globalHeaders.add(new BasicHeader(name, value));
          return this;
      }
docs: Use this method to add one more global header.
  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.