code: private void setResponseLocation(URL url) {
          String location = url.getPath();
          String query = url.getQuery();
          if (query != null) {
              int startOfQuery = location.indexOf(query);
              if (startOfQuery > 0) {
                  location = location.substring(0, startOfQuery);
              }
          }
          connection.getResHeader().add("Location", location);
      }
docs: Router+Handlers