`Kubectl.get(V1EndpointSlice.class)` failed due to `endpoints: null`

[fanyang01]

Describe the bug

It is possible that a service does not have any endpoint, for example, when the corresponding deployment was scaled to zero. In this case, the EndpointSlice API returns endpoints: null. However, it will be rejected by the following validation rule:

https://github.com/kubernetes-client/java/blob/cbd3d1bb2cd1bd2f4aa18b80a1131e810dea9b79/kubernetes/src/main/java/io/kubernetes/client/openapi/models/V1EndpointSlice.java#L329-L332

Client Version 20.0.1

Kubernetes Version 1.29.0-eks-c417bb3

Java Version Java 21

To Reproduce Steps to reproduce the behavior:

• Create a service that cannot select any pod:

kubectl apply -f - <<EOF
apiVersion: v1
kind: Service
metadata:
  name: nginx-service
spec:
  selector:
    app.kubernetes.io/name: proxy
  ports:
  - name: name-of-service-port
    protocol: TCP
    port: 80
    targetPort: http-web-svc
EOF

• The endpoints field will be null:

k get endpointslice nginx-service-t786l -o yaml
addressType: IPv4
apiVersion: discovery.k8s.io/v1
endpoints: null
kind: EndpointSlice
...

Expected behavior

Kubectl.get(V1EndpointSlice.class) would not throw IllegalArgumentException.

Server (please complete the following information):

• OS: Bottlerocket
• Environment: container
• Cloud: AWS

[brendandburns]

Personally, I think this is an issue with how Go handles encoding empty arrays (https://medium.com/swlh/arrays-and-json-in-go-98540f2fa74e)

In practice, if you want to fix this, it needs to be in the upstream code generator, since this parsing is generated by that code generator.