Firebase sign up and login

I am trying to integrate firebase (Google and phone) into play framework. Was able to get through the process of loading the json … From a http client to backend perspective seems like UI passes a firebase token (referring to an unique user) and phone or a password or a email address to the backend. So how do we map/verify this information as well as set up a PLAY_SESSION to add some values specific to that connection ?
Any help is greatly appreciated.

You can lookup how we use firebase auth in play on github:

used in our bootstrap template:

Thank you. That really helped.