}
      return message;
    }
    return null;
  }

  @Override
  protected void afterDone() {
    @RetainedLocalRef ListenableFuture<? extends V> delegate = delegateRef;
    maybePropagateCancellationTo(delegate);

    @RetainedLocalRef Future<?> localTimer = timer;
    // Try to cancel the timer as an optimization.
    // timer may be null if this call to run was by the timer task since there is no happens-before