code: @RequestMapping(value = "/activated", method = RequestMethod.GET)
      public boolean activated(final HttpServletRequest request) {
          return regCenterService.loadActivated().isPresent();
      }
docs: 判断是否存在已连接的注册中心配置.
  
  @param request HTTP请求
  @return 是否存在已连接的注册中心配置