I have deleted google-services.json. Add yours
Implementation Guide
1 - Project
2- Open the Project in your android studio;
3 - IMPORTANT Change the Package Name. (https://stackoverflow.com/questions/16804093/android-studio-rename-package)
4 - Firebase Panel
5 - Create Firebase Project (https://console.firebase.google.com/);
6 - import the file google-service.json into your project