// subclass is implemented with bugs similar to the subclass.
        pendingDescription = "Exception thrown from implementation: " + e.getClass();
      }
      // The future may complete during or before the call to getPendingToString, so we use null
      // as a signal that we should try checking if the future is done again.
      if (!isNullOrEmpty(pendingDescription)) {

  //   unparked.

  /**
   * {@inheritDoc}
   *
   * <p>The default {@link AbstractFuture} implementation throws {@code InterruptedException} if the
   * current thread is interrupted during the call, even if the value is already available.
   *
   * @throws CancellationException {@inheritDoc}
   */
  @CanIgnoreReturnValue
  @Override
  @ParametricNullness