Spring Boot JPA 一对多关系中多方集合丢失内容如何解决？

Question

spring boot jap中一对多关系在多方集合中丢失内容的问题，我的字段结构
@Data
@DynamicUpdate
@DynamicInsert
@Entity(name = "st")
public class St {

@Id
private Long id;
private Long stn;

@OneToMany(mappedBy = "sts")
private Set<Mt> mts;

}

@Data
@DynamicUpdate
@DynamicInsert
@Entity(name = "mt")
public class Mt {

@Id
private Long id;
private Long stn;

@ManyToOne
private St sts;

}

@Override
public Market details(Long id) {
    Optional<St> byId = mtr.findById(1L);
    System.out.println();

// Market market = marketRep.findById(id).orElseThrow(() -> WebException.entityNotFoundException(id));

    return null;
}

很奇怪使用set集合多方字段列表就没有数据，换成list就可以，头很痛xdm