code: func getPersistentVolumeClaimName(set *apps.StatefulSet, claim *v1.PersistentVolumeClaim, ordinal int) string {
  	// NOTE: This name format is used by the heuristics for zone spreading in ChooseZoneForVolume
  	return fmt.Sprintf("%s-%s-%d", claim.Name, set.Name, ordinal)
  }
docs: // getPersistentVolumeClaimName gets the name of PersistentVolumeClaim for a Pod with an ordinal index of ordinal. claim
  // must be a PersistentVolumeClaim from set's VolumeClaims template.