code: public void save(File propertiesFile, String comments) throws IOException {
          FileWriter writer = new FileWriter(propertiesFile);
          _properties.store(writer, comments);
          writer.close();
      }
docs: Saves configuration to a properties file in a format suitable for using {{@link #load(File)}.
  
  @param propertiesFile - a configuration properties file
  @param comments       - a description of the configuration
  @throws IOException