fix issue(#47976)Invalid value error when creating service from exported config

pkg/registry/core/service/strategy.go

@@ -89,7 +89,7 @@ func (svcStrategy) Export(ctx genericapirequest.Context, obj runtime.Object, exa
 		return nil
 	}
 	if t.Spec.ClusterIP != api.ClusterIPNone {
-		t.Spec.ClusterIP = "<unknown>"
+		t.Spec.ClusterIP = ""
 	}
 	if t.Spec.Type == api.ServiceTypeNodePort {
 		for i := range t.Spec.Ports {

pkg/registry/core/service/strategy_test.go

@@ -81,7 +81,7 @@ func TestExportService(t *testing.T) {
 					Namespace: "bar",
 				},
 				Spec: api.ServiceSpec{
-					ClusterIP: "<unknown>",
+					ClusterIP: "",
 				},
 			},
 		},