code: func StorageNodeAffinityToAlphaAnnotation(annotations map[string]string, affinity *v1.NodeAffinity) error {
  	if affinity == nil {
  		return nil
  	}
  
  	json, err := json.Marshal(*affinity)
  	if err != nil {
  		return err
  	}
  	annotations[common.AlphaStorageNodeAffinityAnnotation] = string(json)
  	return nil
  }
docs: // StorageNodeAffinityToAlphaAnnotation converts NodeAffinity type to Alpha annotation for use in PersistentVolumes