How to migrate from GCM to FCM?

This guide will show you how to migrate from use of GCM (Google Cloud Messages) to FCM (Firebase Cloud Messages).
2.) Click -> or Import a google project
How to migrate from GCM to FCM
3.) Click -> Add Firebase to you Android app
How to migrate from GCM to FCM
4.) enter your app package name and press -> Add app
How to migrate from GCM to FCM
5.) download and add file "google-services.json" to you app
How to migrate from GCM to FCM
6.) Add a lines in your build.gradle files (two different files - be careful)
How to migrate from GCM to FCM