dj-rest-auth limit social sign up to a specific email address domain

I’m getting started with dj-rest-auth and I have an app which allows user to only sign in via google. However, I want users to only be able to access my service with a specific google apps email …

Field name `username` is not valid for model

I am attempting to use rest-auth supplied serialisers to GET (*with headers) user details from the defined endpoint /rest-auth/user/ (*with headers (Content-Type: application/json Authorization: …