BasicModel.hasRole will raise an exception with custom entities

Hi guys, maybe is just the lack of good examples on it, but on AeroGear we have an interceptor to authorize requests to our endpoints which relies on "hasRole" method https://github.com/abstractj/aerogear-aerodoc-backend/commit/a8a97fbf638d02d7fa58501705fdf0a92fc1c309

To reproduce the issue just deploy this app, login as john/password: 123 and try to create a new lead.

Here is the stacktrace: https://gist.github.com/abstractj/dbd026beafd94020b159

Maybe we are doing something wrong, but couldn't find anything into the docs.