Use additionalProperties in the CRD OpenAPI spec for Maps of Strings instead of x-kubernetes-preserve-unknown-fields

[scholzj]

As discussed in #7979, we should consider using the additionalProperties field instead of x-kubernetes-preserve-unknown-fields to improve the compatibility with other tools and be more in sync with Kubernetes spec. However, we need to keep in mind:

• That we need to stay backward compatible with existing resources
• We have places where Maps of Objects are used which should stick with ``x-kubernetes-preserve-unknown-fields`

[scholzj]

Should be triaged first to see other views!

[scholzj]

Triaged on 9.2.2023: This can be implemented, but:

• It seems like it should be used only for places where Map<String, String> is used and not where a deeper objects are (e.g. Connector status section)
• Backwards compatibility should be tested
• There is still some risk

[omjikush09]

Hi, Can I work on this?

[scholzj]

You can if you want. But I'm not sure how easy or straight forward it is TBH.

[omjikush09]

Then I don't think it's a great idea for me to work on this if I get stuck with whom I ask for help. 😕