apollo-biz/src/main/java/com/ctrip/framework/apollo/biz/service/ItemService.java/ItemService/findItemsWithoutOrdered
class ItemService:  public List<Item> findItemsWithoutOrdered(String appId, String clusterName, String namespaceName) {
    Namespace namespace = namespaceService.findOne(appId, clusterName, namespaceName);
    if (namespace != null) {
      return findItemsWithoutOrdered(namespace.getId());
    }
    return Collections.emptyList();
  }