如何在Hibernate投影中映射嵌套集合

@Entity
public class Order {
    @Id
    private Long id;
    
    @OneToMany(mappedBy = "order", cascade = CascadeType.ALL)
    private Set<Item> items;
    
    // Getters and setters
}

@Entity
public class Item {
    @Id
    private Long id;
    
    @ManyToOne
    @JoinColumn(name = "order_id")
    private Order order;
    
    @OneToMany(mappedBy = "item", cascade = CascadeType.ALL)
    private Set<SubItem> subItems;
    
    // Getters and setters
}

@Entity
public class SubItem {
    @Id
    private Long id;
    
    @ManyToOne
    @JoinColumn(name = "item_id")
    private Item item;
    
    // Getters and setters
}

Criteria criteria = session.createCriteria(Order.class);
criteria.setFetchMode("items", FetchMode.JOIN);
criteria.setFetchMode("items.subItems", FetchMode.JOIN);
criteria.setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY);

ProjectionList projections = Projections.projectionList();
projections.add(Projections.property("id"), "orderId");
projections.add(Projections.property("items.id"), "itemId");
projections.add(Projections.property("items.subItems.id"), "subItemId");

criteria.setProjection(projections);

List<Map<String, Object>> result = criteria.list();