HQL中出现XXX is not mapped的错误

我的代码如下

    @Test 
    public void testCollection(){
        String hql = "from Order  where orderItems is not empty";
        
        Query query =  session.createQuery(hql);
        
        List<Order> orders = query.list();
        
        for(Order o:orders){
            
            System.out.println(o.getCustomer().getName());
            
            System.out.println(o.getAmount());
        
        }
        
        
    }

由于没有在HQL语句中使用别名，而包里存在一个OrderItem的类，使其编译无法通过，所以将代码改写如下即可运行。

    @Test 
    public void testCollection(){
        String hql = "from Order o where o.orderItems is not empty";
        
        Query query =  session.createQuery(hql);
        
        List<Order> orders = query.list();
        
        for(Order o:orders){
            
            System.out.println(o.getCustomer().getName());
            
            System.out.println(o.getAmount());
        
        }
        
        
    }