As far as I know `getBackReferences` returns all references regardless of permissions. It's an unrestricted access.
This may lead to problems when the user sees only one file.
In this case an explicit permission check for each file must be done and the behavior must be defined, what should happen?
I think a user should not see forward- or back-references when he has no access to the other object.

Can you add tests verifying both, forward- and back-references when the user only has access to one object (no `Access contents information` nor `View`)?