code: func (p *nfsProvisioner) getClassForVolume(pv *v1.PersistentVolume) (*storage.StorageClass, error) {
  	if p.client == nil {
  		return nil, fmt.Errorf("Cannot get kube client")
  	}
  	className := helper.GetPersistentVolumeClass(pv)
  	if className == "" {
  		return nil, fmt.Errorf("Volume has no storage class")
  	}
  	class, err := p.client.StorageV1().StorageClasses().Get(className, metav1.GetOptions{})
  	if err != nil {
  		return nil, err
  	}
  	return class, nil
  }
docs: // getClassForVolume returns StorageClass