code: private String getFilteredText(String filename, String encoding, boolean xmlFiltering) throws IOException {
      if (options.isVerbose()) {
        lt.setOutput(System.err);
      }
      // don't use StringTools.readStream() as that might add newlines which aren't there:
      try (InputStreamReader reader = getInputStreamReader(filename, encoding)) {
        String fileContents = readerToString(reader);
        if (xmlFiltering) {
          return filterXML(fileContents);
        } else {
          return fileContents;
        }
      }
    }
docs: Loads filename and filters out XML. Note that the XML
  filtering can lead to incorrect positions in the list of matching rules.