我有下面的用户实体，用户的配置文件是可选的，当我保存没有配置文件的用户我得到这个错误
ora-01400:无法将null插入（“用户\实体“.”配置文件\ fk”）

@Entity
public class UserEntity implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(generator = "user-uuid")
    @GenericGenerator(name = "user-uuid", strategy = "uuid2")
    private String userId;

    private String email;

    @OneToOne(optional = true, fetch = FetchType.LAZY)
    @MapsId
    @JoinColumn(name = "profile_fk", nullable = true, unique = true)
    private ProfileEntity profile;

}

@Entity
@Inheritance(strategy = InheritanceType.JOINED)
public class ProfileEntity implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(generator = "profile-uuid")
    @GenericGenerator(name = "profile-uuid", strategy = "uuid2")
    private String profileId;

    private String email;

}