state = State.PENDING;
    listeners = new ArrayList<Listener>();
  }

  @CanIgnoreReturnValue
  @Override
  public boolean cancel(boolean mayInterruptIfRunning) {
    if (!state.permitsPublicUserToTransitionTo(State.CANCELLED)) {
      return false;
    }

    this.mayInterruptIfRunning = mayInterruptIfRunning;
    state = State.CANCELLED;
    notifyAndClearListeners();

    if (delegate != null) {