code: private void validateSettingsDir() {
           if (!settingsDir.exists()) {
               throw new RuntimeException(SETTINGS_DIR_OPTION + " : " + settingsDir.getPath() + " does not exist!");
           }
           else if (!settingsDir.isDirectory()) {
               throw new RuntimeException(SETTINGS_DIR_OPTION + " : " + settingsDir.getPath() + " is not a directory!");
           }
       }
docs: Ensure that {@link #settingsDir} exists and is a directory.
  Throws a {@link RuntimeException} if {@link #settingsDir} is invalid.