feat(crd-generator): Add support for WebhookConversion and NonConversion

[baloo42]

Description

Adds support for WebhookConversion and NonConversion to the CRDGenerator.

Refers to #5794

Type of change

• Bug fix (non-breaking change which fixes an issue)
• Feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change
• Chore (non-breaking change which doesn't affect codebase;
  test, version modification, documentation, etc.)

Checklist

• Code contributed by me aligns with current project license: Apache 2.0
• I Added CHANGELOG entry regarding this change
• I have implemented unit tests to cover my changes
• I have added/updated the javadocs and other documentation accordingly
• No new bugs, code smells, etc. in SonarCloud report
• I tested my code in Kubernetes
• I tested my code in OpenShift

TODO

• Don't use abbreviated var names in annotations
  (see feat(crd-generator): Add support for WebhookConversion and NonConversion #5875 (comment))

[baloo42]

This approach introduces two new annotations @WebhookConversion and @NoneConversion. Both annotations will be detected on a custom resource class and decorate the CRD accordingly.
I call this approach "flattened" because I don't use a parent annotation and sub annotations e.g. for the service reference:

WebhookConversion

@Group("sample.fabric8.io")
@Version("v2")
@Kind("WebhookConversion")
@WebhookConversion(versions = { "v2", "v1" }, svcName = "conversion-webhook", svcNamespace = "my-namespace")
public class WebhookConversionExample extends CustomResource<WebhookConversionSpec, Void> {
}

apiVersion: apiextensions.k8s.io/v1
kind: CustomResourceDefinition
metadata:
  name: webhookconversions.sample.fabric8.io
spec:
  conversion:
    strategy: Webhook
    webhook:
      clientConfig:
        service:
          name: conversion-webhook
          namespace: my-namespace
      conversionReviewVersions:
      - v2
      - v1
  group: sample.fabric8.io
  names:
    kind: WebhookConversion
    plural: webhookconversions
    singular: webhookconversion
  scope: Cluster
[...]

NoneConversion

@Group("sample.fabric8.io")
@Version("v1")
@Kind("NoneConversion")
@NoneConversion
public class NoneConversionExample extends CustomResource<NonConversionSpec, Void> {
}

apiVersion: apiextensions.k8s.io/v1
kind: CustomResourceDefinition
metadata:
  name: noneconversions.sample.fabric8.io
spec:
  conversion:
    strategy: None
  group: sample.fabric8.io
  names:
    kind: NoneConversion
    plural: noneconversions
    singular: noneconversion
  scope: Cluster
[...]

Additional Notes

• The annotations will be detected only on custom resource classes.
• The configuration will be validated and the generator will fail if the annotation is used wrong. (e.g. if service reference and url are used at the same time)
• The generator will fail, if the annotations are configured more than one time on the same custom resource kind. (e.g. both annotations or on multiple custom resource versions.

[baloo42]

@andreaTP Can you (or someone else like @csviri) give me a first feedback on this? (any feedback is welcome..)

I will create in parallel another PR to prepare the test environment (Approval Tests and the test module improvements we talked about last week). After this is merged I will add to this PR additional tests.

TBD:

• Is the flattened approach ok or do you prefer more annotations?
• Are abbreviated variables ok or are long names preferred? (e.g. svcName vs serviceName)
• Allow the annotation only on custom resource versions with storage=true?

[andreaTP]

I think that @csviri is much more familiar than me with the subject, and I would appreciate his input on this one.
(I can do it, but is going to take more time)

Quick answers meanwhile:

Is the flattened approach ok or do you prefer more annotations?

I'm, personally, fine with it

Are abbreviated variables ok or are long names preferred?

I think that we are using long names across the codebase, I would keep the current style, e.g.:
https://github.com/search?q=repo%3Afabric8io%2Fkubernetes-client+serviceName&type=code

[sonarqubecloud]

Quality Gate passed

Issues
4 New issues
0 Accepted issues

Measures
0 Security Hotspots
89.5% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[baloo42]

Can probably be closed. See #5885 (comment)

[manusa]

Can probably be closed. See #5885 (comment)

Yes, maybe close it.
Once api-v2 is merged, we might want to add a test there to ensure the feature is working as expected.