Firebase (Notification Service)
Make sure that you’ve implemented Firebase Cloud Messaging SDK according to this instruction.
Pay your attention to the first two paragraphs of this part of the instruction. The third paragraph is optional.
Amplitude (Integrate Analytics)
Implement sending events in Amplitude: you need to send a
push_tokenevent with an event property
token, in which the device token from Firebase is passed.
The event can be dispatched using the
[onNewTokencallback](https://firebase.google.com/docs/cloud-messaging/android/client#monitor-token-generation) in the Firebase SDK.
Alternatively, you can independently check if the token changes every time the application is applied, and send events if it changes.