All things without references have references

What's wrong with the current model?

SCThing has origin: SCThingRemoteOrigin | SCThingUserOrigin.

Each origin has maintainer?: SCPerson | SCOrganization and SCThingRemoteOrigin has responsibleEntity?: SCPerson | SCOrganization.

This is the first bug: origins should only contain SCPersonWithoutReferences and SCOrganizationWithoutReferences.

The second bug is that all things without references directly inherit from SCThing which has origin which contains references. That leads to all things without references to actually having references. This results in an infinite model...

We noticed this while @wulkanat worked on core-tools!8 (merged).

How should the model be instead?

Things without references should not contain references.

Why should the model be that way?

Finite model, no infinite loop while analyzing the model.

cc: @All