How to properly organize sing in from an android smartphone to my server (Spring (REST)) via facebook account?

Question

Java

Briefly describe what is available:

• server on Spring + PostgreSQL, on which the REST api is implemented (completely public)
  
• android application that requests data from the server via REST
  

Now I plan to introduce accounts, but I do not want to force users to register. I think to fasten the entrance through facebook. I can’t google anything more or less intelligible on this issue (little experience in Spring, REST, Facebook api, OAuth).
Please share links to tutorials, implementation examples, documentation. I would very much like to see in the examples the bundle described by me.
Thank you.