private List<UserGroup> getUserGroups() throws RIACheckedException {

        DomainManager domainManager = ComptelObjectStorageEngine.getRealm(Constant.USER_MANAGEMENT_COSE_REALM).getDomainManager();

        List<UserGroup> userGroups = new ArrayList<UserGroup>();
        try {
             QueryResult r = domainManager.query(UserGroup.class, 0, -1, null);
             List<UserGroup> tmpUserGroup = (List<UserGroup>) r.getList();
             userGroups = domainManager.detachAll(tmpUserGroup, null);

        } catch (Exception e) {
            logger.log(Level.WARNING, "Failed to get user groups", e);
            throw new RIACheckedException("Failed to get user groups", e, null, null, null);

        } finally {
            domainManager.close();
        }

        return userGroups;