jpa @NotFound注解

作用是当不用外键关联时，可能会出现为null的情况，默认是会报错的，加上@NotFound( action = NotFoundAction.IGNORE ) 就不会报错。
​​​Person​​代码：

@Data
@ToString(exclude="phones")
@Entity(name = "Person")
public class Person {
    @Id
    @GeneratedValue
    private Long id;
    private String name;
    @ManyToOne( fetch = FetchType.LAZY )
//    @NotFound( action = NotFoundAction.IGNORE )
    @JoinColumn( // 注意：这里没有加外键啊
            name = "cityName",
            referencedColumnName = "name",
            insertable = false,
            updatable = false
    )
    private City city;
    private String cityName;
    public void setCityName(String cityName){
        this.cityName=cityName;
    }
}

​​City​​代码：

@Data
@Entity
@Table( name = "City" )
public  class City implements Serializable {
    @Id
    @GeneratedValue
    private Long id;
    private String name;
}

city数据 1，New York
person数据 1，John Doe，Atlantis
这里的​​​Atlantis​​​ 明显关联不上 ​​New York​​

测试代码：

Person person = entityManager.find( Person.class, 1L );
assertEquals( "Atlantis", person.getCityName() );
assertNull( null, person.getCity() );

理想效果： 不加​​@NotFound( action = NotFoundAction.IGNORE )​​​会报错
加了不报错
实测没加，也没有报错。why??