fieldmanager: remove dependencies on internal

Remove dependencies on internal fieldmanager for admission things. This
is preparing for moving fieldmanager out, but the admission part will
stay here, so it can't depend directly on internal.

Kubernetes-commit: d13b405307262b2b9c0795af3a22d0a5725ef6a0

pkg/endpoints/handlers/fieldmanager/admission.go

@@ -22,7 +22,6 @@ import (
 
 	"k8s.io/apimachinery/pkg/api/meta"
 	"k8s.io/apiserver/pkg/admission"
-	"k8s.io/apiserver/pkg/endpoints/handlers/fieldmanager/internal"
 	"k8s.io/apiserver/pkg/warning"
 )
 
@@ -71,7 +70,7 @@ func (admit *managedFieldsValidatingAdmissionController) Admit(ctx context.Conte
 		return err
 	}
 	managedFieldsAfterAdmission := objectMeta.GetManagedFields()
-	if _, err := internal.DecodeManagedFields(managedFieldsAfterAdmission); err != nil {
+	if err := ValidateManagedFields(managedFieldsAfterAdmission); err != nil {
 		objectMeta.SetManagedFields(managedFieldsBeforeAdmission)
 		warning.AddWarning(ctx, "",
 			fmt.Sprintf(InvalidManagedFieldsAfterMutatingAdmissionWarningFormat,

pkg/endpoints/handlers/fieldmanager/admission_test.go

@@ -27,7 +27,6 @@ import (
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apiserver/pkg/admission"
 	"k8s.io/apiserver/pkg/endpoints/handlers/fieldmanager"
-	"k8s.io/apiserver/pkg/endpoints/handlers/fieldmanager/internal"
 	"sigs.k8s.io/structured-merge-diff/v4/fieldpath"
 )
 
@@ -36,7 +35,9 @@ func TestAdmission(t *testing.T) {
 	ac := fieldmanager.NewManagedFieldsValidatingAdmissionController(wrap)
 	now := metav1.Now()
 
-	validFieldsV1, err := internal.SetToFields(*fieldpath.NewSet(fieldpath.MakePathOrDie("metadata", "labels", "test-label")))
+	validFieldsV1 := metav1.FieldsV1{}
+	var err error
+	validFieldsV1.Raw, err = fieldpath.NewSet(fieldpath.MakePathOrDie("metadata", "labels", "test-label")).ToJSON()
 	if err != nil {
 		t.Fatal(err)
 	}