CreateOrderReq传入参数校验不能为空，为什么没生效呢？

package com.imooc.mall.controller;

import com.imooc.mall.common.ApiRestResponse;
import com.imooc.mall.model.request.CreateOrderReq;
import com.imooc.mall.service.OrderService;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;

import javax.annotation.Resource;
import javax.validation.Valid;

@RestController
public class OrderController {
    @Resource
    OrderService orderService;
    @PostMapping("order/create")
    public ApiRestResponse create(@Valid @RequestBody CreateOrderReq createOrderReq){
        String orderNo = orderService.create(createOrderReq);
        return ApiRestResponse.success(orderNo);
    }
}

package com.imooc.mall.model.request;

import javax.validation.constraints.NotNull;

public class CreateOrderReq {
    @NotNull(message = "收件人姓名不能为null")
    private String receiverName;
    @NotNull(message = "收件人手机号不能为null")
    private String receiverMobile;
    @NotNull(message = "收件人地址不能为null")
    private String receiverAddress;

    private Integer orderStatus;

    private Integer postage;

    private Integer paymentType;

    public String getReceiverName() {
        return receiverName;
    }

    public void setReceiverName(String receiverName) {
        this.receiverName = receiverName;
    }

    public String getReceiverMobile() {
        return receiverMobile;
    }

    public void setReceiverMobile(String receiverMobile) {
        this.receiverMobile = receiverMobile;
    }

    public String getReceiverAddress() {
        return receiverAddress;
    }

    public void setReceiverAddress(String receiverAddress) {
        this.receiverAddress = receiverAddress;
    }

    public Integer getOrderStatus() {
        return orderStatus;
    }

    public void setOrderStatus(Integer orderStatus) {
        this.orderStatus = orderStatus;
    }

    public Integer getPostage() {
        return postage;
    }

    public void setPostage(Integer postage) {
        this.postage = postage;
    }

    public Integer getPaymentType() {
        return paymentType;
    }

    public void setPaymentType(Integer paymentType) {
        this.paymentType = paymentType;
    }
}