return future instanceof FluentFuture
        ? (FluentFuture<V>) future
        : new ForwardingFluentFuture<V>(future);
  }

  /**
   * Simply returns its argument.
   *
   * @deprecated no need to use this
   * @since 28.0
   */
  @Deprecated
  public static <V extends @Nullable Object> FluentFuture<V> from(FluentFuture<V> future) {

})
abstract class AbstractTransformFuture<
        I extends @Nullable Object, O extends @Nullable Object, F, T extends @Nullable Object>
    extends FluentFuture.TrustedFuture<O> implements Runnable {
  static <I extends @Nullable Object, O extends @Nullable Object> ListenableFuture<O> createAsync(
      ListenableFuture<I> input,
      AsyncFunction<? super I, ? extends O> function,