apollo-adminservice/src/main/java/com/ctrip/framework/apollo/adminservice/controller/AppController.java/AppController/get
class AppController:  @GetMapping("/apps/{appId:.+}")
  public AppDTO get(@PathVariable("appId") String appId) {
    App app = appService.findOne(appId);
    if (app == null) {
      throw new NotFoundException("app not found for appId " + appId);
    }
    return BeanUtils.transform(AppDTO.class, app);
  }