@J2ktIncompatible
@ElementTypesAreNonnullByDefault
// TODO(dpb): GWT compatibility.
public final class ClosingFuture<V extends @Nullable Object> {

  private static final LazyLogger logger = new LazyLogger(ClosingFuture.class);

  /**
   * An object that can capture objects to be closed later, when a {@link ClosingFuture} pipeline is
   * done.
   */
  public static final class DeferredCloser {