code: public void start()
      {
          Preconditions.checkState(state.compareAndSet(State.LATENT, State.STARTED), "Cannot be started more than once");
  
          Preconditions.checkState(!executorService.isShutdown(), "Already started");
          Preconditions.checkState(!hasLeadership, "Already has leadership");
  
          client.getConnectionStateListenable().addListener(listener);
          requeue();
      }
docs: Attempt leadership. This attempt is done in the background - i.e. this method returns
  immediately.<br><br>
  <b>IMPORTANT: </b> previous versions allowed this method to be called multiple times. This
  is no longer supported. Use {@link #requeue()} for this purpose.