getIdToken returns expired token

[ashley-arta]

In the documentation, it says getIdToken will always return a valid token, even if forceRefresh is false. However, during our testing, we found cases where the jwt token returned has expired for about 90 seconds on Android.

In FlutterFirebaseAuthPlugin.java, it's calling the close-source FirebaseUser code
GetTokenResult tokenResult = Tasks.await(firebaseUser.getIdToken(forceRefresh)); and I can't find any code that checks the validity of the token. This method also doesn't say in the documentation that the token is valid https://firebase.google.com/docs/reference/android/com/google/firebase/auth/FirebaseUser#getIdToken(boolean).

Maybe I missed something... how is the validity of the jwt token guaranteed?