} else {
      collection = ImmutableList.copyOf(futures);
    }
    return (ListenableFuture<? extends T>[]) collection.toArray(new ListenableFuture<?>[0]);
  }

  // This can't be a TrustedFuture, because TrustedFuture has clever optimizations that
  // mean cancel won't be called if this Future is passed into setFuture, and then
  // cancelled.
  private static final class InCompletionOrderFuture<T extends @Nullable Object>

@SuppressWarnings("ShortCircuitBoolean")
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,

  @Override
  final void addInitialException(Set<Throwable> seen) {
    checkNotNull(seen);
    if (!isCancelled()) {
      /*
       * requireNonNull is safe because:
       *
       * - This is a TrustedFuture, so tryInternalFastPathGetFailure will in fact return the failure
       *   cause if this Future has failed.
       *
       * - And this future *has* failed: This method is called only from handleException (through

  /**
   * A less abstract subclass of AbstractFuture. This can be used to optimize setFuture by ensuring
   * that {@link #get} calls exactly the implementation of {@link AbstractFuture#get}.
   */
  abstract static class TrustedFuture<V extends @Nullable Object> extends FluentFuture<V>
      implements AbstractFuture.Trusted<V> {
    @CanIgnoreReturnValue
    @Override
    @ParametricNullness