docs: private static String getAndCheckOption(Configuration config, ConfigOption<String> primaryOption, ConfigOption<String> fallbackOption) {
  		String value = config.getString(primaryOption, config.getString(fallbackOption));
  		if (value != null) {
  			return value;
  		}
  		else {
  			throw new IllegalConfigurationException("The config option " + primaryOption.key() +
  					" or " + fallbackOption.key() + " is missing.");
  		}
  	}