code: func getExtraSupplementalGid(volumeGidValue string, pod *v1.Pod) (int64, bool) {
  	if volumeGidValue == "" {
  		return 0, false
  	}
  
  	gid, err := strconv.ParseInt(volumeGidValue, 10, 64)
  	if err != nil {
  		return 0, false
  	}
  
  	if pod.Spec.SecurityContext != nil {
  		for _, existingGid := range pod.Spec.SecurityContext.SupplementalGroups {
  			if gid == int64(existingGid) {
  				return 0, false
  			}
  		}
  	}
  
  	return gid, true
  }
docs: // getExtraSupplementalGid returns the value of an extra supplemental GID as
  // defined by an annotation on a volume and a boolean indicating whether the
  // volume defined a GID that the pod doesn't already request.