default String optionString(String name){
  List<String> allStrings=optionStrings(name);
  if (allStrings.size() > 1) {
    throw new RuntimeException("More than one value specified for option: " + name);
  }
  return allStrings.isEmpty() ? null : allStrings.get(0);
}

default String optionString ( String name ) { List < String > allStrings = optionStrings ( name ) ; if ( allStrings . size ( ) > 1 ) { throw new RuntimeException ( "More than one value specified for option: " + name ) ; } return allStrings . isEmpty ( ) ? null : allStrings . get ( 0 ) ; }
returns a single value for option or null if not present .
