我在Spring应用程序中遇到字段'id'没有默认值的错误。我尝试使用@Post方法创建一个申请人，但在创建申请人时，需要创建新的creditRating对象。
方法如下

public Applicant create(ApplicantDTO applicantDTO) {
        Applicant applicant = ApplicantMapper.toEntity(applicantDTO);
        applicant.setCreditRating(creditRatingService.create());
        return applicantRepository.save(applicant);
    }

这是我的申请人类

@Data
@NoArgsConstructor
@AllArgsConstructor
@Entity
@Table(name = "applicant")
public class Applicant {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private Long identificationNumber;
    private String firstName;
    private String lastName;
    private double monthlyIncome;
    private String phoneNumber;

    @OneToOne(cascade = CascadeType.ALL)
    @JoinColumn(name = "credit_rating_id", referencedColumnName = "id")
    private CreditRating creditRating;

    @OneToOne(cascade = CascadeType.ALL)
    @JoinTable(name = "applicant_credit",
            joinColumns = {@JoinColumn(name = "applicant_id")},
            inverseJoinColumns = {@JoinColumn(name = "credit_id")}
    )
    private Credit credit;

}

这是CreditRating对象的创建方法。

public CreditRating create() {
        CreditRating creditRating = new CreditRating();
        creditRating.setCreditRating(getRandomCreditRating());
        return creditRatingRepository.save(creditRating);
    }

我希望在创建一个申请人时创建这个对象，但是不知何故，我认为JPA不能为它生成id，因为我是这样做的。
此处为信用评级实体

@Data
@Entity
@AllArgsConstructor
@NoArgsConstructor
@Table(name = "credit_rating")
public class CreditRating {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private int creditRating;

}