func startHorizontalPodAutoscalerControllerWithRESTClient(ctx context.Context, controllerContext ControllerContext, controllerName string) (controller.Interface, bool, error) {

	clientConfig := controllerContext.ClientBuilder.ConfigOrDie("horizontal-pod-autoscaler")
	hpaClient := controllerContext.ClientBuilder.ClientOrDie("horizontal-pod-autoscaler")

	apiVersionsGetter := custom_metrics.NewAvailableAPIsGetter(hpaClient.Discovery())

type TestClientBuilder struct {
	clientset clientset.Interface
}

func (TestClientBuilder) Config(name string) (*restclient.Config, error) { return nil, nil }
func (TestClientBuilder) ConfigOrDie(name string) *restclient.Config {
	return &restclient.Config{}
}

func (TestClientBuilder) Client(name string) (clientset.Interface, error) { return nil, nil }

	client := controllerContext.ClientBuilder.ClientOrDie("disruption-controller")
	config := controllerContext.ClientBuilder.ConfigOrDie("disruption-controller")
	scaleKindResolver := scale.NewDiscoveryScaleKindResolver(client.Discovery())
	scaleClient, err := scale.NewForConfig(config, controllerContext.RESTMapper, dynamic.LegacyAPIPathResolverFunc, scaleKindResolver)

	if !controllerContext.ComponentConfig.GarbageCollectorController.EnableGarbageCollector {
		return nil, true, fmt.Errorf("storage version migrator requires garbage collector")
	}

	config := controllerContext.ClientBuilder.ConfigOrDie(controllerName)
	client := controllerContext.ClientBuilder.ClientOrDie(controllerName)
	informer := controllerContext.InformerFactory.Storagemigration().V1alpha1().StorageVersionMigrations()

			return nil, true, fmt.Errorf("error parsing root-ca-file at %s: %v", controllerContext.ComponentConfig.SAController.RootCAFile, err)
		}
	} else {
		rootCA = controllerContext.ClientBuilder.ConfigOrDie("root-ca-cert-publisher").CAData
	}

	sac, err := rootcacertpublisher.NewPublisher(
		controllerContext.InformerFactory.Core().V1().ConfigMaps(),
		controllerContext.InformerFactory.Core().V1().Namespaces(),

	// the ratelimiter negatively affects its speed.  Deleting 100 total items in a namespace (that's only a few of each resource
	// including events), takes ~10 seconds by default.
	nsKubeconfig := controllerContext.ClientBuilder.ConfigOrDie("namespace-controller")
	nsKubeconfig.QPS *= 20
	nsKubeconfig.Burst *= 100
	namespaceKubeClient := clientset.NewForConfigOrDie(nsKubeconfig)

	sharedInformers := informers.NewSharedInformerFactoryWithOptions(versionedClient, ResyncPeriod(s)(), informers.WithTransform(trim))

	metadataClient := metadata.NewForConfigOrDie(rootClientBuilder.ConfigOrDie("metadata-informers"))
	metadataInformers := metadatainformer.NewSharedInformerFactoryWithOptions(metadataClient, ResyncPeriod(s)(), metadatainformer.WithTransform(trim))