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

    String username = userInfoHolder.getUser().getUserId();
    item.setDataChangeLastModifiedBy(username);

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