JAVA USER LOGIN/LOGOUT

//------GET USER TOKEN-------
FirebaseUser mUser = FirebaseAuth.getInstance().getCurrentUser();
mUser.getToken(true)
        .addOnCompleteListener(new OnCompleteListener<GetTokenResult>() {
            public void onComplete(@NonNull Task<GetTokenResult> task) {
                if (task.isSuccessful()) {
                    String idToken = task.getResult().getToken();
                      // ...
                }
            }
        });