code: private static TileMatrix getTileMatrixAtLengthIndex(
  			List<TileMatrix> tileMatrices, int index) {
  		return tileMatrices.get(tileMatrices.size() - index - 1);
  	}
docs: Get the tile matrix represented by the current length index
  
  @param tileMatrices
  tile matrices
  @param index
  index location in sorted lengths
  @return tile matrix