如何检查实体多对多关系是否已更改？

Question

I have a user and user has roles.

I retrieved the user from repo and he has 3 roles. I add one more role to user and at some point I call UnitOfWork to find out if user has got new roles?

But getOriginalEntityData(user) does not return this. I see I can use getScheduledCollectionUpdates but I am not sure how to deal with it.