  void onComplete(const Status& status, ContextImpl& context) const override {
    auto& completion_state = context.getCompletionState(this);
    if (completion_state.is_completed_) {
      return;
    }
    if (++completion_state.number_completed_children_ == verifiers_.size() ||
        Status::Ok != status) {
      completion_state.is_completed_ = true;
      completeWithStatus(status, context);
    }
  }
  void onComplete(const Status& status, ContextImpl& context) const override {
    auto& completion_state = context.getCompletionState(this);
    if (completion_state.is_completed_) {
      return;
    }
    if (++completion_state.number_completed_children_ == verifiers_.size() ||
        Status::Ok != status) {
      completion_state.is_completed_ = true;
      completeWithStatus(status, context);
    }
  }