docs: public RegionInfo queryRegionInfo(String accessKey, String bucket) throws QiniuException {
          RegionIndex index = new RegionIndex(accessKey, bucket);
          RegionInfo info = regions.get(index);
          if (info == null) {
              UCRet ret = getRegionJson(index);
              try {
                  info = RegionInfo.buildFromUcRet(ret);
              } catch (Exception e) {
                  e.printStackTrace();
              }
  
              if (info != null) {
                  regions.put(index, info);
              }
          }
          return info;
      }