What happened?

I was testing the new kubectl alpha kuberc set command (added in kubernetes/kubernetes#135003) in the local environment.
I discovered what appears to be unintended behavior when updating existing configurations without specifying --option flags.

When updating an existing defaults/alias entry with --overwrite but without any --option flags, the existing options are cleared (set to nil).

I wrote a simple test case to verify this behavior:
ref: https://github.com/kubernetes/kubernetes/blob/master/staging/src/k8s.io/kubectl/pkg/cmd/kuberc/set_test.go

{ name: "overwrite existing defaults without options", existingKuberc: `apiVersion: kubectl.config.k8s.io/v1beta1 kind: Preference defaults: - command: get  options:  - name: output  default: wide `, options: SetOptions{ Section: sectionDefaults, Command: "get", Options: []string{}, // No options Overwrite: true, }, expectedPref: &v1beta1.Preference{ Defaults: []v1beta1.CommandDefaults{ { Command: "get", Options: nil, // existing options are cleared }, }, }, },

The test passes, which means the current implementation clears existing options when --overwrite is used without any --option flags.
In the same way, for alias, without specifying --option flags, existing options are also cleared.

What did you expect to happen?

Existing options are preserved when --options flags is not provided.
I am not sure this behavior is intentional or not.

How can we reproduce it (as minimally and precisely as possible)?

1. Clone kubernetes/kubernetes repository
2. Add the test case above to staging/src/k8s.io/kubectl/pkg/cmd/kuberc/set_test.go
3. Run: go test ./staging/src/k8s.io/kubectl/pkg/cmd/kuberc/

Anything else we need to know?

I can submit a follow-up PR if this behavior is considered unintended.
Either way, I think adding explicit test cases for this behavior would be valuable to document the intended design.

Kubernetes version

Cloud provider

OS version

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Install tools

Container runtime (CRI) and version (if applicable)

Related plugins (CNI, CSI, ...) and versions (if applicable)