return requireNonNull(v);
    }
    if (future instanceof InternalFutureFailureAccess) {
      Throwable throwable =
          InternalFutures.tryInternalFastPathGetFailure((InternalFutureFailureAccess) future);
      if (throwable != null) {
        return new Failure(throwable);
      }
    }
    boolean wasCancelled = future.isCancelled();

      this.callback = callback;
    }

    @Override
    public void run() {
      if (future instanceof InternalFutureFailureAccess) {
        Throwable failure =
            InternalFutures.tryInternalFastPathGetFailure((InternalFutureFailureAccess) future);
        if (failure != null) {
          callback.onFailure(failure);
          return;
        }
      }
      final V value;
      try {