private boolean isSystemOrSuperUser() throws IOException {
    return Superusers.isSuperUser(VisibilityUtils.getActiveUser());
  }
Verify, when servicing an RPC, that the caller is the scanner owner. If so, we assume that
access control is correctly enforced based on the checks performed in preScannerOpen()
hbase-server/src/main/java/org/apache/hadoop/hbase/security/visibility/VisibilityController.java