Build a super parent class
Some models, like TrustedGrant (https://solid.github.io/data-interoperability-panel/specification/#datamodel-trusted-grant), have properties linked to different models, that can be very diverse (eg for TrustedGrant: Agent, ApplicationRegistrySet, AccessGrantRegistrySet, AccessReceiptRegistrySet).
So, I would like to write a field with a ForeignKey linked to a general model. As, maybe, a super parent class that would be parent of all classes. But not sure at all it is a good idea.