fix: x-kubernetes-preserve-unknown-fields incorrectly applied on List<T>

[rgrama]

Describe the bug

PreserveUnknownFieldsAttribute can currently only be applied to properties. If within my CRD I have a List and I set the attribute, it will render in the CRD at the items level, not within the object itself.

To reproduce

[KubernetesEntity(Group = "test.io", Kind = "Test", ApiVersion = "v1")]
public partial class TestCrd : CustomKubernetesEntity<TestSpec> { }

public class TestSpec
{
    [PreserveUnknownFields]
    public List<Item> Items { get; set; } = default!;
}

public class Item
{
    public string Name { get; set; } = default!;
}

Generates

  - name: v1
    schema:
      openAPIV3Schema:
        properties:
          spec:
            properties:
              items:
                items:
                  properties:
                    name:
                      type: string
                  type: object
                type: array
                x-kubernetes-preserve-unknown-fields: true
            type: object
        type: object

Expected behavior

x-kubernetes-preserve-unknown-fields: true should be applied to the object within items

  - name: v1
    schema:
      openAPIV3Schema:
        properties:
          spec:
            properties:
              items:
                items:
                  properties:
                    name:
                      type: string
                  type: object
                  x-kubernetes-preserve-unknown-fields: true
                type: array
            type: object
        type: object

To achieve this result, the attribute should be allowed on classes

[KubernetesEntity(Group = "test.io", Kind = "Test", ApiVersion = "v1")]
public partial class TestCrd : CustomKubernetesEntity<TestSpec> { }

public class TestSpec
{
    public List<Item> Items { get; set; } = default!;
}

[PreserveUnknownFields]
public class Item
{
    public string Name { get; set; } = default!;
}

[buehler]

Absolutely, very nice addition!

Just one thing: would you mind to add some tests for the new behavior?

Much appreciated!

[rgrama]

Added a couple of tests

[rgrama]

btw I have one more change on my local branch which I require - handling of object. Currently object or List< object > is not supported. Should i do that as a separate PR or can I add to this one?

[buehler]

it would be really cool to have it in a separate PR

[rgrama]

alright, I'll create a separate one tomorrow