docs: public static void transformFile(Source stylesheetFile, File input, File output) throws TransformerException {
      TransformerFactory factory = TransformerFactory.newInstance();
      factory.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, true);
      Transformer transformer = factory.newTransformer(stylesheetFile);
      transformer.setOutputProperty(OutputKeys.INDENT, "yes");
      transformer.transform(new StreamSource(input), new StreamResult(output));
    }