修复订单取消/退款之后优惠券没有返还问题 (#397)

litemall-db/src/main/java/org/linlinjava/litemall/db/service/LitemallCouponUserService.java

@@ -91,4 +91,10 @@ public class LitemallCouponUserService {
         example.or().andStatusEqualTo(CouponUserConstant.STATUS_USABLE).andEndTimeLessThan(LocalDateTime.now()).andDeletedEqualTo(false);
         return couponUserMapper.selectByExample(example);
     }
+
+    public List<LitemallCouponUser> findByOid(Integer orderId) {
+        LitemallCouponUserExample example = new LitemallCouponUserExample();
+        example.or().andOrderIdEqualTo(orderId).andDeletedEqualTo(false);
+        return couponUserMapper.selectByExample(example);
+    }
 }