The last failing test, I'm not sure it should pass.

Anyway this allows cluster resources to be used as additional related resources. Uses * namespace as a wildcard (user is expected to understand the implications and do any manual filtering)

hi @splitice , thank for PR, however introducing support for cluster level resources requires introducing an API versioning scheme, which is not done yet.

I'm interested in this one too, as I also have a use case for cluster scoped relatedResources.
In my case I have namespace scoped parents and children, but include info from a related cluster scoped resource

Closing, #496 need to be implemented first, later on work on #345