[WIP] Fix parsing of Knative Service YAML in version 1.4.0

[Copilot]

• Understand the issue: getSerializationType incorrectly treats Knative Services as K8s Services
• Update getSerializationType to check if API group is built-in
• Return undefined for non-built-in groups so they're treated as KubernetesObject
• Add test case for Knative Service YAML parsing
• Add test case for custom resources
• Update util_test.ts to test the new behavior
• Run existing tests to ensure no regressions
• Verify fix with manual testing
• Format code with prettier

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Incorrectly parsing Knative Service YAML in 1.4.0</issue_title>
<issue_description>Describe the bug
When using the loadYaml method to parse a Knative Service YAML, version 1.4.0 incorrectly handles the parsing and loses the spec content. This appears to be a regression as it works correctly in version 1.3.0.

Client Version
e.g. 1.4.0

Server Version
e.g. N/A

To Reproduce
Steps to reproduce the behavior:

const k8s = require('@kubernetes/client-node');

const x = k8s.loadYaml(`apiVersion: serving.knative.dev/v1
kind: Service
metadata:
  name: hello-world
spec:
  template:
    spec:
      containers:
        - image: ghcr.io/knative/helloworld-go:latest
          ports:
            - containerPort: 8080
          env:
            - name: TARGET
              value: "World"`);
console.log(JSON.stringify(x, null, 2));

Actual Behavior (1.4.0)

{
  "apiVersion": "serving.knative.dev/v1",
  "kind": "Service",
  "metadata": {
    "name": "hello-world"
  },
  "spec": {}
}

Expected behavior (1.3.0)
The parsed object maintains the complete structure including all spec content:

{
  "apiVersion": "serving.knative.dev/v1",
  "kind": "Service",
  "metadata": {
    "name": "hello-world"
  },
  "spec": {
    "template": {
      "spec": {
        "containers": [
          {
            "image": "ghcr.io/knative/helloworld-go:latest",
            "ports": [
              {
                "containerPort": 8080
              }
            ],
            "env": [
              {
                "name": "TARGET",
                "value": "World"
              }
            ]
          }
        ]
      }
    }
  }
}

---

It appears that the parser might be incorrectly treating the Knative Service as a native Kubernetes Service, causing it to lose the Knative-specific spec configuration.

</issue_description>

<agent_instructions>Update the getSerializationType function so that it considers the API group in determining the type and it returns undefined if the api group is not one of the build-in Kubernetes api groups or empty string.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

@brendandburns Yeah, this is caused by this here: https://github.com/kubernetes-client/javascript/blob/main/src/util.ts#L168

In general, parsing to non-built in objects isn't really well supported, we should augment the loadYaml function so that it considers the API group.</comment_new>

Fixes #2670

---

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[brendandburns]

Generally looks good, but I think the code could be simplified by returning KubernetesObject rather than undefined when the API group is not a built-in API.

[brendandburns]

Return 'KubernetesObject' here.

[brendandburns]

Rather than requiring the caller to do this, just modify getSerializationType to return KubernetesOjbect for the non-native case.

[kevinjgraff]

Suggested change

	const version = gv.version.charAt(0).toUpperCase() + gv.version.slice(1);
	const version = gv.version ? gv.version.charAt(0).toUpperCase() + gv.version.slice(1) : '';

Perhaps add check so code doesn't throw when gv.version is undefined or malformed. (Keep getSerializationType protected for edge cases)