}
        };
    Bar bar = getDone(transform(future, function, directExecutor()));
    assertSame(barChild, bar);
  }

  /*
   * Android does not handle this stack overflow gracefully... though somehow some other
   * stack-overflow tests work. It must depend on the exact place the error occurs.
   */
  @AndroidIncompatible
  @J2ktIncompatible
  @GwtIncompatible // StackOverflowError

import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A step in a pipeline of an asynchronous computation. When the last step in the computation is
 * complete, some objects captured during the computation are closed.
 *
 * <p>A pipeline of {@code ClosingFuture}s is a tree of steps. Each step represents either an

  }

  // Inner Classes

  /**
   * Segments are specialized versions of hash tables. This subclass inherits from ReentrantLock
   * opportunistically, just to simplify some locking and avoid separate construction.
   */
  @SuppressWarnings("serial") // This class is never serialized.
  static class Segment<K, V> extends ReentrantLock {

    /*