docs: public void writeExtractedMsgs(
        SoyMsgBundle msgBundle,
        OutputFileOptions options,
        ByteSink output,
        ErrorReporter errorReporter)
        throws IOException {
  
      CharSequence cs = msgPlugin.generateExtractedMsgsFile(msgBundle, options, errorReporter);
      output.asCharSink(UTF_8).write(cs);
    }