code: public void onStartup() throws StartupException {
          if (monitor == null) {
              monitor = this;
              thread = new Thread() {
                  @Override
                  public void run() {
                      this.setName("UserGroupMonitor-thread");
                      monitor.start();
                  }
              };
              thread.start();
          }
      }
docs: Invoked when the server starts up.