docs: protected String quadTree(final long pMapTileIndex) {
  		final StringBuilder quadKey = new StringBuilder();
  		for (int i = MapTileIndex.getZoom(pMapTileIndex); i > 0; i--) {
  			int digit = 0;
  			final int mask = 1 << (i - 1);
  			if ((MapTileIndex.getX(pMapTileIndex) & mask) != 0)
  				digit += 1;
  			if ((MapTileIndex.getY(pMapTileIndex) & mask) != 0)
  				digit += 2;
  			quadKey.append("" + digit);
  		}
  
  		return quadKey.toString();
  	}