code: @CommandArgument
    public void stop() {
      try {
        jobHub.shutdown();
        jobHub = null;
        Registry registry = getRegistry();
        registry.unbind("AuthenticationService");
        System.out.println("Hub stopped");
      } catch (Exception e) {
        logger.error("An error occurred while stopping the hub", e);
        System.err.println("Hub did not shut down cleanly, see log for details.");
      }
    }
docs: Stops the hub.