code: func newPersistentVolumeLabel() *persistentVolumeLabel {
  	// DEPRECATED: in a future release, we will use mutating admission webhooks to apply PV labels.
  	// Once the mutating admission webhook is used for AWS, Azure, GCE, and OpenStack,
  	// this admission controller will be removed.
  	klog.Warning("PersistentVolumeLabel admission controller is deprecated. " +
  		"Please remove this controller from your configuration files and scripts.")
  	return &persistentVolumeLabel{
  		Handler: admission.NewHandler(admission.Create),
  	}
  }
docs: // newPersistentVolumeLabel returns an admission.Interface implementation which adds labels to PersistentVolume CREATE requests,
  // based on the labels provided by the underlying cloud provider.
  //
  // As a side effect, the cloud provider may block invalid or non-existent volumes.