@Size(min = 1, message = “不能少于1个好友”)
private List<@Valid UserInfo> friends;

public void init() {
    validator = Validation.buildDefaultValidatorFactory().getValidator(); //初始化验证器
    userInfo = new UserInfo(); //初始化待验证对象
    userInfo.setId("1");
    userInfo.setUsername("zzz");
    userInfo.setPassword("zzzzzzz");
    userInfo.setEmail("88888@qq.com");
    userInfo.setAge(18);
    Calendar calendar = Calendar.getInstance();
    calendar.set(2020, Calendar.FEBRUARY, 1);
    userInfo.setBirthday(calendar.getTime());

    UserInfo friend = new UserInfo();
    friend.setId("2");
    friend.setUsername("xxx");
    friend.setPassword("xxxxxxx");
    friend.setEmail("99999@qq.com");
    friend.setAge(55);
    List<UserInfo> friends = new ArrayList<>();
    friends.add(friend);
    userInfo.setFriends(friends);
}

控制台打印

十二月 08, 2020 8:09:02 下午 org.hibernate.validator.internal.util.Version <clinit>
INFO: HV000001: Hibernate Validator 6.0.16.Final
UserInfo(id=1, username=zzz, password=zzzzzzz, email=88888@qq.com, phone=null, age=18, birthday=Sat Feb 01 20:09:02 CST 2020, friends=[UserInfo(id=2, username=xxx, password=xxxxxxx, email=99999@qq.com, phone=null, age=55, birthday=null, friends=null)])

进程已结束，退出代码 0

测试时，集合中只有一个对象，而集合中这个对象的friends集合并没有初始化也没有填充
为什么级联验证时，没有再次验证集合中friend这个实例的friends集合属性