return waitFor(closingCallable, ClosingCallable.class);
    }

    @SuppressWarnings("unchecked") // proxy for a generic class
    <V> AsyncClosingCallable<V> waitFor(AsyncClosingCallable<V> asyncClosingCallable) {
      return waitFor(asyncClosingCallable, AsyncClosingCallable.class);
    }

    @SuppressWarnings("unchecked") // proxy for a generic class

  }

  /**
   * An operation that computes a {@link ClosingFuture} of a result.
   *
   * @param <V> the type of the result
   * @since 30.1
   */
  public interface AsyncClosingCallable<V extends @Nullable Object> {
    /**
     * Computes a result, or throws an exception if unable to do so.
     *
     * <p>Any objects that are passed to {@link DeferredCloser#eventuallyClose(Object, Executor)

  }

  /**
   * An operation that computes a {@link ClosingFuture} of a result.
   *
   * @param <V> the type of the result
   * @since 30.1
   */
  @FunctionalInterface
  public interface AsyncClosingCallable<V extends @Nullable Object> {
    /**
     * Computes a result, or throws an exception if unable to do so.
     *
     * <p>Any objects that are passed to {@link DeferredCloser#eventuallyClose(Object, Executor)