code: public static void add() {
  
          String current = System.getProperties().getProperty(HANDLER_PKGS, "");
          if (current.length() > 0) {
              if (current.contains(PKG)) {
                  return;
              }
              current = current + "|";
          }
          System.getProperties().put(HANDLER_PKGS, current + PKG);
  
      }
docs: Adds the protocol handler.