private static final ListenerCallQueue.Event<Listener> STARTING_EVENT =
      new ListenerCallQueue.Event<Listener>() {
        @Override
        public void call(Listener listener) {
          listener.starting();
        }

        @Override
        public String toString() {
          return "starting()";
        }
      };
  private static final ListenerCallQueue.Event<Listener> RUNNING_EVENT =

  private static final ListenerCallQueue.Event<Listener> STARTING_EVENT =
      new ListenerCallQueue.Event<Listener>() {
        @Override
        public void call(Listener listener) {
          listener.starting();
        }

        @Override
        public String toString() {
          return "starting()";
        }
      };
  private static final ListenerCallQueue.Event<Listener> RUNNING_EVENT =

    void enqueueStoppedEvent() {
      listeners.enqueue(STOPPED_EVENT);
    }

    void enqueueHealthyEvent() {
      listeners.enqueue(HEALTHY_EVENT);
    }

    void enqueueFailedEvent(Service service) {
      listeners.enqueue(
          new ListenerCallQueue.Event<Listener>() {
            @Override
            public void call(Listener listener) {
              listener.failure(service);
            }

    Listener listener;
    synchronized (this) {
      listener = listeners.get(state);
    }

    if (code == null || listener == null) {
      return new MockResponse()
          .setResponseCode(404)
          .setBody("unexpected request");
    }

    try {
      OAuthSession session = slackApi.exchangeCode(code, redirectUrl());
      listener.sessionGranted(session);

  /**
   * Registers a listener to be {@linkplain Executor#execute(Runnable) run} on the given executor.
   * The listener will run when the {@code Future}'s computation is {@linkplain Future#isDone()
   * complete} or, if the computation is already complete, immediately.
   *
   * <p>There is no guaranteed ordering of execution of listeners, but any listener added through

  /**
   * Registers a listener to be {@linkplain Executor#execute(Runnable) run} on the given executor.
   * The listener will run when the {@code Future}'s computation is {@linkplain Future#isDone()
   * complete} or, if the computation is already complete, immediately.
   *
   * <p>There is no guaranteed ordering of execution of listeners, but any listener added through

  /**
   * Registers a listener to be {@linkplain Executor#execute(Runnable) run} on the given executor.
   * The listener will run when the {@code Future}'s computation is {@linkplain Future#isDone()
   * complete} or, if the computation is already complete, immediately.
   *
   * <p>There is no guaranteed ordering of execution of listeners, but any listener added through

   */
  public void addListener(L listener, Executor executor) {
    checkNotNull(listener, "listener");
    checkNotNull(executor, "executor");
    listeners.add(new PerListenerQueue<>(listener, executor));
  }

  /**
   * Enqueues an event to be run on currently known listeners.
   *
   * <p>The {@code toString} method of the Event itself will be used to describe the event in the
   * case of an error.

   * <p>RuntimeExceptions thrown by a listener will be caught and logged. Any exception thrown
   * during {@code Executor.execute} (e.g., a {@code RejectedExecutionException}) will be caught and
   * logged.
   *
   * @param listener the listener to run when the service changes state is complete
   * @param executor the executor in which the listeners callback methods will be run. For fast,

        this.componentName = componentName;
    }

    /**
     * Returns the onDestroy listener.
     * @return The onDestroy listener.
     */
    public OnDestroyListener<T> getOnDestroyListener() {
        return onDestroyListener;
    }

    /**
     * Sets the onDestroy listener.
     * @param onDestroyListener The OnDestroyListener to set.
     */