code: static void writeServiceFile(Collection<String> services, OutputStream output)
        throws IOException {
      BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(output, UTF_8));
      for (String service : services) {
        writer.write(service);
        writer.newLine();
      }
      writer.flush();
    }
docs: Writes the set of service class names to a service file.
  
  @param output not {@code null}. Not closed after use.
  @param services a not {@code null Collection} of service class names.
  @throws IOException