public Room registerRoom(Room room) {
    int index = rooms.indexOf(room);
    if (index == -1) {
      addRoom(room);
      return room;
    } else {
      Room foundedRoom = rooms.get(index);
      Iterator<Row> rows = room.getAllRows();
      while (rows.hasNext()) {
        foundedRoom.registerRow(rows.next());
      }
      return foundedRoom;
    }
  }