Allow for unknown fields in the CRD Spec

[kelhelawy]

Hi,
I know I can use @PreserveUnknownFields in fields inside the specs to allow for unknown fields, but is there a way to do so in the specs itself (the parent), not a field inside?
In the CRD it is possible by doing so:

spec:
  group: "..."
  names:
    kind: "..."
  scope: "Namespaced"
  versions:
  - name: "v1"
    schema:
      openAPIV3Schema:
        properties:
          spec:
            x-kubernetes-preserve-unknown-fields: true
            properties:
               ....

But what would be the equivalent of that from java,
The annotation PreserveUnknownFields is not allowed on type

[baloo42]

At the moment I think this is not possible because of the missing target in the annotation. See #6740

Once this is implemented, this should be possible in the same way like described for @Required in the docs.