@Test
public void test_01() {

    final Member member = new Member("asd@asd.com", "name");
    final Coupon coupon = new Coupon(member);
    final List<Coupon> coupons = new ArrayList<>();
    coupons.add(coupon);
    member.setCoupons(coupons);
    System.out.println(member.toString());
}