code: public List<ExtendedRelation> getRelations(String baseTable,
  			String baseColumn, String relatedTable, String relatedColumn,
  			String relation, String mappingTable) throws SQLException {
  
  		List<ExtendedRelation> relations = null;
  
  		try {
  			if (extendedRelationsDao.isTableExists()) {
  				relations = extendedRelationsDao.getRelations(baseTable,
  						baseColumn, relatedTable, relatedColumn, relation,
  						mappingTable);
  			} else {
  				relations = new ArrayList<>();
  			}
  		} catch (SQLException e) {
  			throw new GeoPackageException(
  					"Failed to get relationships. Base Table: " + baseTable
  							+ ", Base Column: " + baseColumn
  							+ ", Related Table: " + relatedTable
  							+ ", Related Column: " + relatedColumn
  							+ ", Relation: " + relation + ", Mapping Table: "
  							+ mappingTable, e);
  		}
  
  		return relations;
  	}
docs: Get the relations matching the non null provided values
  
  @param baseTable
  base table name
  @param baseColumn
  base primary column name
  @param relatedTable
  related table name
  @param relatedColumn
  related primary column name
  @param relation
  relation name
  @param mappingTable
  mapping table name
  @return extended relations
  @throws SQLException
  upon failure
  @since 3.2.0