Oracle jpa 不能插入空值

如何解决Oracle jpa 不能插入空值

我有以下用户实体，用户的个人资料是可选的，当我保存没有个人资料的用户时，我收到此错误

ORA-01400：无法将空值插入 ("USER_ENTITY"."PROFILE_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;

}