private void relay(String message, Connection sender) {
        synchronized (authenticatedClients) {
            for (Connection connection : authenticatedClients) {
                try {
                    if (connection != sender) {
                        connection.getDataOutputStream().writeUTF(message);
                    }
                } catch (IOException ex) {
                    Logger.getLogger(Server.class.getName()).log(Level.SEVERE, null, ex);
                }
            }
        }
    }