docs: private static void _transform(Source source, Result out) throws TransformerException {
          TransformerFactory factory = TransformerFactory.newInstance();
          factory.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, true);
  
          // this allows us to use UTF-8 for storing data,
          // plus it checks any well-formedness issue in the submitted data.
          Transformer t = factory.newTransformer();
          t.transform(source, out);
      }