public function getItems(bool $force = false) : CNabuCatalogItemList
    {
        if ($this->nb_tree_child_list->isEmpty() || $force) {
            $this->nb_tree_child_list->merge(
                CNabuCatalogItem::buildObjectListFromSQL(
                    'nb_catalog_item_id',
                    'SELECT *
                       FROM nb_catalog_item
                      WHERE nb_catalog_id=%catalog_id$d
                        AND nb_catalog_item_parent_id=%parent_id$d
                      ORDER BY nb_catalog_item_order ASC',
                    array(
                        'catalog_id' => $this->getCatalogId(),
                        'parent_id' => $this->getId()
                    ),
                    $this->getCatalog()
                )
            );
        }

        return $this->nb_tree_child_list;
    }