* {@link MapNode} which additionally preserves user-supplied ordering. This node represents a data instance of
* a {@code list} with {@code ordered-by user;} substatement and a {@code key} definition.
*/
-public interface UserMapNode extends MapNode, OrderedNodeContainer<MapEntryNode> {
+public non-sealed interface UserMapNode extends MapNode, OrderedNodeContainer<MapEntryNode> {
@Override
default Class<UserMapNode> contract() {
return UserMapNode.class;