message: Try to deal with g++ warnings.
diff: @@ -33,6 +33,9 @@ class MockServerLifecycleNotifier2 : public MockServerLifecycleNotifier {
  public:
  MockServerLifecycleNotifier2() = default;
  ~MockServerLifecycleNotifier2() override = default;
  +
  + using MockServerLifecycleNotifier::registerCallback;
  +
  ServerLifecycleNotifier::HandlePtr
  registerCallback(Stage stage, StageCallbackWithCompletion callback) override {
  return registerCallback2(stage, callback);
  