code: func (kl *Kubelet) GetExtraSupplementalGroupsForPod(pod *v1.Pod) []int64 {
  	return kl.volumeManager.GetExtraSupplementalGroupsForPod(pod)
  }
docs: // GetExtraSupplementalGroupsForPod returns a list of the extra
  // supplemental groups for the Pod. These extra supplemental groups come
  // from annotations on persistent volumes that the pod depends on.