apollo-portal/src/main/java/com/ctrip/framework/apollo/portal/controller/ItemController.java/ItemController/createItem
class ItemController:  @PreAuthorize(value = "@permissionValidator.hasModifyNamespacePermission(#appId, #namespaceName, #env)")
  @PostMapping("/apps/{appId}/envs/{env}/clusters/{clusterName}/namespaces/{namespaceName}/item")
  public ItemDTO createItem(@PathVariable String appId, @PathVariable String env,
                            @PathVariable String clusterName, @PathVariable String namespaceName,
                            @RequestBody ItemDTO item) {
    checkModel(isValidItem(item));

    //protect
    item.setLineNum(0);
    item.setId(0);
    String userId = userInfoHolder.getUser().getUserId();
    item.setDataChangeCreatedBy(userId);
    item.setDataChangeLastModifiedBy(userId);
    item.setDataChangeCreatedTime(null);
    item.setDataChangeLastModifiedTime(null);

    return configService.createItem(appId, Env.valueOf(env), clusterName, namespaceName, item);
  }