code: public static String createR2ClientLimiterKey(Config config) {
  
      String urlTemplate = config.getString(HttpConstants.URL_TEMPLATE);
      try {
        String escaped = URIUtil.encodeQuery(urlTemplate);
        URI uri = new URI(escaped);
        if (uri.getHost() == null)
          throw new RuntimeException("Cannot get host part from uri" + urlTemplate);
  
        String key = uri.getScheme() + "/" + uri.getHost();
        if (uri.getPort() > 0) {
          key = key + "/" + uri.getPort();
        }
        log.info("Get limiter key [" + key + "]");
        return key;
      } catch (Exception e) {
        throw new RuntimeException("Cannot create R2 limiter key", e);
      }
    }
docs: Convert D2 URL template into a string used for throttling limiter
  
  Valid:
  d2://host/${resource-id}
  
  Invalid:
  d2://host${resource-id}, because we cannot differentiate the host