/**
   * Returns the {@link Throwable} that caused this service to fail.
   *
   * @throws IllegalStateException if this service's state isn't {@linkplain State#FAILED FAILED}.
   * @since 14.0
   */
  Throwable failureCause();

  /**
   * Registers a {@link Listener} to be {@linkplain Executor#execute executed} on the given
   * executor. The listener will have the corresponding transition method called whenever the

    delegate.addListener(listener, executor);
  }

  /**
   * @since 14.0
   */
  @Override
  public final Throwable failureCause() {
    return delegate.failureCause();
  }

  /**
   * @since 15.0
   */
  @CanIgnoreReturnValue
  @Override
  public final Service startAsync() {
    delegate.startAsync();
    return this;
  }

    delegate.addListener(listener, executor);
  }

  /**
   * @since 14.0
   */
  @Override
  public final Throwable failureCause() {
    return delegate.failureCause();
  }

  /**
   * @since 15.0
   */
  @CanIgnoreReturnValue
  @Override
  public final Service startAsync() {
    delegate.startAsync();
    return this;
  }

  /**
   * Returns the {@link Throwable} that caused this service to fail.
   *
   * @throws IllegalStateException if this service's state isn't {@linkplain State#FAILED FAILED}.
   * @since 14.0
   */
  Throwable failureCause();

  /**
   * Registers a {@link Listener} to be {@linkplain Executor#execute executed} on the given
   * executor. The listener will have the corresponding transition method called whenever the

        };
    Callable<@Nullable Void> completeExceptionallyRunnable =
        new Callable<@Nullable Void>() {
          final Exception failureCause = new Exception("setException");

          @Override
          public @Nullable Void call() {
            if (currentFuture.get().setException(failureCause)) {
              numSuccessfulSetCalls.incrementAndGet();
            }
            awaitUnchecked(barrier);
            return null;

        };
    Callable<@Nullable Void> completeExceptionallyRunnable =
        new Callable<@Nullable Void>() {
          final Exception failureCause = new Exception("setException");

          @Override
          public @Nullable Void call() {
            if (currentFuture.get().setException(failureCause)) {
              numSuccessfulSetCalls.incrementAndGet();
            }
            awaitUnchecked(barrier);
            return null;

  private static final class FailedService extends Throwable {
    FailedService(Service service) {
      super(
          service.toString(),
          service.failureCause(),
          false /* don't enable suppression */,
          false /* don't calculate a stack trace. */);
    }
  }

  private static final class FailedService extends Throwable {
    FailedService(Service service) {
      super(
          service.toString(),
          service.failureCause(),
          false /* don't enable suppression */,
          false /* don't calculate a stack trace. */);
    }
  }