public String getLatestVersion() {
   HttpServletRequest request = getRequest();
   HttpServletResponse response = getResponse();
   Version versionLast = versionService.getLatestVersion(clientType);
   Map<String, Object> map = new HashMap<String, Object>();
   if (versionLast != null && versionLast.getVersion() > version) {
     map.put("url", versionLast.getUrl());
     map.put("version", versionLast.getVersion());
     map.put("name", versionLast.getName());
     map.put("content", versionLast.getContent());
     map.put("upgradeType", versionLast.getUpgradeType());
   }
   AjaxResponseUtil.returnData(request, response, "", map);
   return null;
 }