apollo-portal/src/main/java/com/ctrip/framework/apollo/portal/service/ItemService.java/ItemService/createCommentItem
class ItemService:  public ItemDTO createCommentItem(String appId, Env env, String clusterName, String namespaceName, ItemDTO item) {
    NamespaceDTO namespace = namespaceAPI.loadNamespace(appId, env, clusterName, namespaceName);
    if (namespace == null) {
      throw new BadRequestException(
          "namespace:" + namespaceName + " not exist in env:" + env + ", cluster:" + clusterName);
    }
    item.setNamespaceId(namespace.getId());

    return itemAPI.createCommentItem(appId, env, clusterName, namespaceName, item);
  }