fix(addon): remove internal annotation from v1alpha1 after conversion (#1321)

When converting ManagedClusterAddOn from v1beta1 to v1alpha1, the
internal annotation 'addon.open-cluster-management.io/v1alpha1-install-namespace'
should be removed after being converted to Spec.InstallNamespace field.

This annotation is only used internally for v1beta1 storage to preserve
the InstallNamespace field which was removed in v1beta1. It should not
appear in v1alpha1 API responses.

Fixes: ACM-28133

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Signed-off-by: Qing Hao <qhao@redhat.com>
Co-authored-by: Claude Sonnet 4.5 <noreply@anthropic.com>

pkg/addon/webhook/v1beta1/managedclusteraddon_conversion.go

@@ -48,6 +48,9 @@ func (src *ManagedClusterAddOn) ConvertTo(dstRaw conversion.Hub) error {
 	// This field was removed in v1beta1, so we store it in annotation
 	if installNs, ok := src.Annotations[InstallNamespaceAnnotation]; ok {
 		v1alpha1Obj.Spec.InstallNamespace = installNs
+		// Remove the internal annotation from v1alpha1 object
+		// This annotation is only used for v1beta1 storage, not for v1alpha1 API
+		delete(v1alpha1Obj.Annotations, InstallNamespaceAnnotation)
 	}
 
 	// Manually populate deprecated ConfigReferent field in ConfigReferences

pkg/addon/webhook/v1beta1/managedclusteraddon_conversion_test.go

@@ -106,9 +106,8 @@ func TestManagedClusterAddOnConvertTo(t *testing.T) {
 					ObjectMeta: metav1.ObjectMeta{
 						Name:      "test-addon",
 						Namespace: "cluster1",
-						Annotations: map[string]string{
-							"addon.open-cluster-management.io/v1alpha1-install-namespace": "test-namespace",
-						},
+						// The internal annotation should be removed after conversion to v1alpha1
+						Annotations: map[string]string{},
 					},
 					Spec: addonv1alpha1.ManagedClusterAddOnSpec{
 						InstallNamespace: "test-namespace",
@@ -178,6 +177,43 @@ func TestManagedClusterAddOnConvertTo(t *testing.T) {
 				},
 			},
 		},
+		{
+			name: "conversion removes internal annotation but preserves user annotations",
+			src: &ManagedClusterAddOn{
+				ManagedClusterAddOn: addonv1beta1.ManagedClusterAddOn{
+					ObjectMeta: metav1.ObjectMeta{
+						Name:      "test-addon",
+						Namespace: "cluster1",
+						Annotations: map[string]string{
+							"addon.open-cluster-management.io/v1alpha1-install-namespace": "test-namespace",
+							"abc.def":         "hahaha",
+							"user.annotation": "should-be-preserved",
+						},
+					},
+					Spec: addonv1beta1.ManagedClusterAddOnSpec{},
+				},
+			},
+			expected: &internalv1alpha1.ManagedClusterAddOn{
+				ManagedClusterAddOn: addonv1alpha1.ManagedClusterAddOn{
+					TypeMeta: metav1.TypeMeta{
+						Kind:       "ManagedClusterAddOn",
+						APIVersion: "addon.open-cluster-management.io/v1alpha1",
+					},
+					ObjectMeta: metav1.ObjectMeta{
+						Name:      "test-addon",
+						Namespace: "cluster1",
+						// Internal annotation removed, user annotations preserved
+						Annotations: map[string]string{
+							"abc.def":         "hahaha",
+							"user.annotation": "should-be-preserved",
+						},
+					},
+					Spec: addonv1alpha1.ManagedClusterAddOnSpec{
+						InstallNamespace: "test-namespace",
+					},
+				},
+			},
+		},
 	}
 
 	for _, tc := range cases {