code: protected URLConnection createURLConnection() throws Exception {
          URL url = getResourceURL();
          if (url == null) return null;
          URLConnection uc = url.openConnection();
          // encoding should be applied when connecting
          return uc;
      }
docs: Optional: creates a URL connection to access the resource.
  By default, tries to connect to the {@linkplain #getResourceURL() resource URL}.
  @return URL connection
  @throws Exception