protected void remove() {
   getSlash();
   for (User user : super.getUsersSet()) {
     this.removeUsers(user.getUsername());
     user.remove();
   }
   deleteDomainObject();
 }
 protected void removeUsers(String username) throws IllegalRemovalException, UserUnknownException {
   hasUser(username);
   if (username.equals(ROOT_USER)) throw new IllegalRemovalException(username);
   else {
     User toRemove = getUserByUsername(username);
     toRemove.remove();
     super.removeUsers(toRemove);
   }
 }