apollo-portal/src/main/java/com/ctrip/framework/apollo/portal/controller/AppController.java/AppController/findApps
class AppController:  @GetMapping
  public List<App> findApps(@RequestParam(value = "appIds", required = false) String appIds) {
    if (Strings.isNullOrEmpty(appIds)) {
      return appService.findAll();
    }
    return appService.findByAppIds(Sets.newHashSet(appIds.split(",")));
  }