I have been authenticating user from facebook on firebase but i want to make them set their phone numbers linked to the user but i cant find any way to make them set their phone number i can only retrieve using FirebaseUser user.getPhoneNumber and update phonenumber needs credentials not string which i don't know how to use so can anyone help me ?!
FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();
user.getPhoneNumber();
user.updatePhoneNumber();