### Question:
ListStreamDemo { public static String list2String(List<String> list){ return list.parallelStream().collect(Collectors.joining(",")); }  static String list2String(List<String> list); static String list2String2(List<String> list); static List<Student> distinctBy(List<Student> students);  }### Answer:
@Test void list2String() { log.info("string result: {}", ListStreamDemo.list2String(list)); }