How to implement stateless cookie authentication using Play Silhouette?

The below link says that you can use CookieAuthenticator as stateless or stateful.

http://silhouette.mohiva.com/docs/authenticator

But I cannot see any options to make the choice at the below link.

http://silhouette.mohiva.com/v3.0/docs/config-authenticators#cookieauthenticator

I have copied the implementation for the below example. Is this stateless or stateful? If its stateful how can I implement stateless authentication?

https://github.com/mohiva/play-silhouette-seed