go composition function: observed XR managedFields leak into SSA status patch

internal/xfn/utils.go、特に AsStruct() から始め、SSA ステータスパッチが構築される composition_functions.go を確認します。crossplane render と metadata.managedFields を含むクラスターのレスポンスとの差分を再現し、そのフィールドが目的の composite resource に到達する箇所を追跡します。生成された構造体のラウンドトリップによって拒否される SSA ステータスパッチが生成されなくなり、managedFields のカバレッジが追加されれば完了です。

What happened?

I am using the Crossplane project sturcture generating the go structs for the composed and composite
resources. The object retains the ManagedFields from the request and when set to the response via

    mapAny, err := runtime.DefaultUnstructuredConverter.ToUnstructured(goStructOfComposite)
    unstr := unstructured.Unstructured{Object: mapAny}
    response.SetDesiredCompositeResource(rsp, &resource.Composite{Resource: &composite.Unstructured{Unstructured: unstr}}),

the metadata.managedFields populated by the API server survive into the SSA patch
body, and Kubernetes rejects it

Below is an analysis by Claude:

When a Go composition function round-trips the observed XR through a generated
struct and calls response.SetDesiredCompositeResource, the
metadata.managedFields populated by the API server survive into the SSA patch
body, and Kubernetes rejects it:

cannot apply composite resource status: metadata.managedFields must be nil

AsStruct() (L52–76)
copies the full observed XR backing map into the RunFunctionRequest proto
without stripping managedFields. Generated ObjectMeta structs include
ManagedFields *[]ManagedFieldsEntry, so the field survives the Go struct
round-trip and reaches the
SSA patch in composition_functions.go,
where Kubernetes rejects it.

crossplane render does not populate managedFields
in the observed XR proto, so render passes while the cluster fails.

Workaround: call unstr.SetManagedFields(nil) before SetDesiredCompositeResource.

Related: crossplane/crossplane#7453

What environment did it happen in?
Crossplane version: v2.3.2, v2.3.