code: public void load() throws IOException {
          if (resource.toExternalForm().endsWith(".xml")) {
              // XML Format
              bundle = new XMLResourceBundle(resource.openStream());
          } else {
              // Properties file (loaded using UTF-8)
              bundle = new UTF8PropertiesResourceBundle(resource.openStream());
          }
  
          if (bundle.keySet().isEmpty()) {
              throw new IOException(resource.toExternalForm() + " is not a valid resource - no keys");
          }
      }
docs: Loads the content of the I18N Extension by reading the content of {@link #resource}.
  
  @throws IOException if the content cannot be loaded