resultSets.add(
new UpcastIterator<EntityContainer, WayContainer>(
new WayContainerIterator(new WayReader(dbCtx, "box_way_list"))));
resultSets.add(
new UpcastIterator<EntityContainer, RelationContainer>(
new RelationContainerIterator(new RelationReader(dbCtx, "box_relation_list"))));
// Merge all readers into a single result iterator and return.
return new MultipleSourceIterator<EntityContainer>(resultSets);
} catch (SQLException e) {