提交事务时无法提交JPA事务/错误

Question

我的代码： 我无法提交JPA交易；嵌套的异常是javax.persistence.RollbackException：提交事务时出错。

 <spring-boot.version>2.0.3.RELEASE</spring-boot.version>

当classeB具有classeC的集合时发生错误

@Service
public class ServiceImpl implements Service{

    private Repository repository;

    @Autowired
    public ServiceImpl(Repository repository) {
        this.repository = repository;
    }

    @Transactional
    public CLASSEA add(Long id, CLASSEB classeB) {
        Optional<CLASSEA > optionalClasseA = repository.findById(id);

        if (optionalClasseA.isPresent()) {
            CLASSEA classA= optionalClasseA .get();
            classA.addClasseB(classeB);
            return repository.save(classA);
        }

        return null;
    }
}

休眠实体：

@Entity
public class CLASSEA implements Serializable {
    @OneToMany(mappedBy = "classeA", cascade = CascadeType.ALL)
    @Cache(usage = CacheConcurrencyStrategy.NONSTRICT_READ_WRITE)
    private Set<CLASSEB> classB= new HashSet<>();
}

public class CLASSEB implements Serializable {
    @OneToMany(mappedBy = "classeB", cascade = CascadeType.MERGE)
    @Cache(usage = CacheConcurrencyStrategy.NONSTRICT_READ_WRITE)
    private Set<CLASSEC> classeC= new HashSet<>();

    @ManyToOne
    @JsonIgnoreProperties("paymentItems")
    private ClasseA classeA;

}

@Entity
public class CLASSEC implements Serializable {
   @ManyToOne
   private CLASSEB classeB;
}

POST请求：

classe B : {
    "amount": 7845,
    "classeC": [ {  ..
    }],
    "classeA": null,

    "day": "2018-07-19T10:46:04.245+02:00",
    "id": null
}