code: @Override
      public void loadGroups(Collection<TileGroup> groups)
      {
          groupTiles.clear();
          tilesGroup.clear();
          groupTypes.clear();
  
          for (final TileGroup group : groups)
          {
              final String name = group.getName();
              groupTiles.put(name, group.getTiles());
              groupTypes.put(name, group.getType());
              for (final TileRef tile : group.getTiles())
              {
                  tilesGroup.put(tile, name);
              }
          }
      }
docs: /*
  MapTileGroup