hibernate如何实现包装类查询？

Question

hibernate官网里使用包装类的例子，

public class PersonWrapper {

    private final Long id;

    private final String nickName;

    public PersonWrapper(Long id, String nickName) {
        this.id = id;
        this.nickName = nickName;
    }
    public Long getId() {
        return id;
    }
    public String getNickName() {
        return nickName;
    }
}
CriteriaBuilder builder = entityManager.getCriteriaBuilder();
CriteriaQuery<PersonWrapper> criteria = builder.createQuery( PersonWrapper.class );
Root<Person> root = criteria.from( Person.class );
Path<Long> idPath = root.get( Person_.id );
Path<String> nickNamePath = root.get( Person_.nickName);
criteria.select( builder.construct( PersonWrapper.class, idPath, nickNamePath ) );
criteria.where( builder.equal( root.get( Person_.name ), "John Doe" ) );
List<PersonWrapper> wrappers = entityManager.createQuery( criteria ).getResultList();

但是Person_整死不知道是什么东西？