MapStruct：在映射到另一个对象列表时，在对象列表中获取空值

Question

我在映射到另一个对象列表时在对象列表中获取空值。

Dto Classes :(考虑在dto类中生成的getter / setter）

public class Customer {
    private Long id;
    private String name;
    private Collection<OrderItem> orderItems;
}

public class OrderItem {
    private String name;
    private Long quantity;
}

public class CustomerDto {
    public Long id;
    public String customerName;
    public List<OrderItemDto> orders;
}

public class OrderItemDto {
    public String name;
    public Long quantity;
}

映射器：

    @Mapper(uses = { OrderItemMapper.class })
public interface CustomerMapper {

    CustomerMapper MAPPER = Mappers.getMapper( CustomerMapper.class );

    @Mappings({
        @Mapping(source = "orders", target = "orderItems"),
        @Mapping(source = "customerName", target = "name")
    })
    Customer toCustomer(CustomerDto customerDto);

    @InheritInverseConfiguration
    CustomerDto fromCustomer(Customer customer);
}

    @Mapper
public interface OrderItemMapper {

    OrderItemMapper MAPPER = Mappers.getMapper(OrderItemMapper.class);

    @Mappings({
        @Mapping(source = "name", target = "name"),
        @Mapping(source = "quantity", target = "quantity")
    })
    OrderItem toOrder(OrderItemDto orderItemDto);

    @InheritInverseConfiguration
    OrderItemDto fromOrder(OrderItem orderItem);
}

测试类：

 public class App {
    public static void main(String[] args) {

        CustomerDto customerDto = new CustomerDto();
        customerDto.id = 10L;
        customerDto.customerName = "Filip";
        OrderItemDto order1 = new OrderItemDto();
        order1.name = "Table";
        order1.quantity = 2L;

        ArrayList<OrderItemDto> tmpOrders = new ArrayList<OrderItemDto>();
        tmpOrders.add(order1);
        customerDto.setOrders(tmpOrders);

        for (OrderItemDto order : customerDto.getOrders()) {
            System.out.println(" order items = " + order.toString());
        }

        Customer customer = CustomerMapper.MAPPER.toCustomer(customerDto);

        System.out.println(" id ==== " + customer.getId());
        System.out.println("getName == " + customer.getName());

        for (OrderItem order : customer.getOrderItems()) {
            System.out.println(" order items = " + order.toString());
        }
    }
}

我得到的输出为：

order items = name = Table , qty = 2
id ==== 10
getName ==Filip

order items = name = null , qty = null

这里我得到Order Object（name，qty）的空值

我不明白这段代码中缺少什么。