Look at the code whether you user this function
* line 49 of in this file: `GetAppInfo();` .
* line 106 of `application/application_instance.cc`: `SendSyncReply(current_app->GetAppInfo().Serialize().c_str());`

I would say this API is not very needed, I'd suggest to init the `app_info_` in the constructor. And call `Serialize()` when needed.