code: private void checkSuperUser() throws AccessControlException {
      // collects user and groups
      String user = AuthenticatedClientUser.getClientUser(ServerConfiguration.global());
      List<String> groups = getGroups(user);
      if (!isPrivilegedUser(user, groups)) {
        throw new AccessControlException(ExceptionMessage.PERMISSION_DENIED
            .getMessage(user + " is not a super user or in super group"));
      }
    }
docs: Checks whether the user is a super user or in super group.
  
  @throws AccessControlException if the user is not a super user