public List<String> getUsers()
    {
        List<String> ret = new ArrayList<>();
        final ConcurrentMap<String, ConcurrentHashSet<String>> user2session = Session.get().getApplication()
                        .getMetaData(ConnectionRegistry.USER2SESSION);
        if (user2session != null) {
            ret = new ArrayList<>(user2session.keySet());
        }
        return ret;
    }
public List < String > getUsers ( ) { List < String > ret = new ArrayList < > ( ) ; final ConcurrentMap < String , ConcurrentHashSet < String > > user2session = Session . get ( ) . getApplication ( ) . getMetaData ( ConnectionRegistry . USER2SESSION ) ; if ( user2session != null ) { ret = new ArrayList < > ( user2session . keySet ( ) ) ; } return ret ; }
@return list of all registered Users