How to get additional paths fields in HWIOAuthBundle?

Question

symfony

Installed HWIOAuthBundle, crossed with FOSUB and all is well. The only trouble is that the User entity has a firstName property. I spent several hours to set this property to the appropriate value from Facebook. In the config I do this:

resource_owners:
    facebook:
        type: facebook
        client_id: XXXXXX
        client_secret: XXXXXX
        scope: "public_profile,email,user_photos"
        paths:
            first_name: first_name

This does not work. Perhaps someone has come across this package and can tell you how to configure it to receive fields other than "email, username"?