I need a Java Develop

I have a back-end server (Java), I am implementing the fast registration via Firebase to my project, on the client side I can take the TokenID and send it to the server, now I should verify the authenticity of this TokenID and get some info such as: email, name and surname.
Useful links:
https://firebase.google.com/docs/auth/admin/verify-id-tokens
https://firebase.google.com/docs/database/rest/auth
https://firebase.google.com/docs/reference/rest/auth/#section-verify-custom-token