private synchronized boolean removeConnecion(Connection connection) {
    Socket socket = connection.getSocket();
    if (!socket.isClosed()) {
      try {
        socket.close();
      }
      catch (IOException e) {
        // closing failed ?!
        return false;
      }
    }
    boolean toReturn = connections.remove(connection);
    // TEST MESSAGE
    System.out.println("Connection stopped!. Connected users: " + connections.size());
    return toReturn;
  }