code: public List<ContentsId> getIds(String type) {
  
  		List<ContentsId> contentsIds = null;
  
  		ContentsDao contentsDao = geoPackage.getContentsDao();
  
  		try {
  
  			if (contentsIdDao.isTableExists()) {
  
  				QueryBuilder<Contents, String> contentsQueryBuilder = contentsDao
  						.queryBuilder();
  				QueryBuilder<ContentsId, Long> contentsIdQueryBuilder = contentsIdDao
  						.queryBuilder();
  
  				contentsQueryBuilder.where()
  						.eq(Contents.COLUMN_DATA_TYPE, type);
  				contentsIdQueryBuilder.join(contentsQueryBuilder);
  
  				contentsIds = contentsIdQueryBuilder.query();
  
  			} else {
  				contentsIds = new ArrayList<>();
  			}
  		} catch (SQLException e) {
  			throw new GeoPackageException(
  					"Failed to query for contents id by contents data type. GeoPackage: "
  							+ geoPackage.getName() + ", Type: " + type, e);
  		}
  
  		return contentsIds;
  	}
docs: Get by contents data type
  
  @param type
  contents data type
  @return contents ids