code: @Override
  	protected void validateContents(Contents contents) {
  		// Verify the Contents have a tiles data type
  		ContentsDataType dataType = contents.getDataType();
  		if (dataType == null
  				|| (dataType != ContentsDataType.TILES && dataType != ContentsDataType.GRIDDED_COVERAGE)) {
  			throw new GeoPackageException("The "
  					+ Contents.class.getSimpleName() + " of a "
  					+ TileTable.class.getSimpleName()
  					+ " must have a data type of "
  					+ ContentsDataType.TILES.getName() + " or "
  					+ ContentsDataType.GRIDDED_COVERAGE.getName());
  		}
  	}
docs: {@inheritDoc}