我有两个模型用户和角色，这是一个多对多的关系。我需要添加一个用户，并给他一个已经存在于我的数据库中的特定角色------用户------

@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
@ToString

@Entity
@Table(name = "user")
public class User {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name="user_Id")
    private int userId;
    @Column(name="name")
    private String name;
    @Column(name="lastname")
    private String lastname;
    @Column(name="email")
    private String email;
    @Column(name="password")
    private String password;
    @Column(name="isActive")
    private boolean isActive;
    @Column(name="lastActive")
    private String lastActive;
    @Column(name="createdDate")
    private String createdDate;
    @Column(name="isBlocked")
    private boolean isBlocked;

    @ManyToOne(fetch = FetchType.LAZY, optional = false)
    @JoinColumn(name = "institution_id", nullable = false)
    @JsonIgnoreProperties(value = {"user"})
    private Institution institution;

    @ManyToMany(fetch = FetchType.LAZY, cascade = {CascadeType.PERSIST, CascadeType.DETACH,CascadeType.MERGE,CascadeType.REFRESH})
    @JoinTable(name = "user_has_role",
            joinColumns = {
                    @JoinColumn(name = "user_id", referencedColumnName = "user_id",
                            nullable = false, updatable = true)},
            inverseJoinColumns = {
                    @JoinColumn(name = "role_id", referencedColumnName = "role_id",
                            nullable = false, updatable = true)})
    @JsonIgnoreProperties(value = {"users"})
    private Set<Role> roles = new HashSet<>();

}

--------角色--------

@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
@ToString

@Entity
@Table(name = "role")
public class Role {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name="role_Id")
    private int roleId;
    @Column(name="name")
    private String name;
    @Column(name="description")
    private String description;
    @ManyToMany(mappedBy = "roles", fetch = FetchType.LAZY)
    @JsonIgnoreProperties(value = {"roles"})
    private Set<User> users = new HashSet<>();

}

以及应用程序的控制器

@PostMapping("/addUser")
    public String addUser(@RequestBody User user) {
        userrepository.save(user);
        return "user saved with name: " + user.getName();
    }

这是我随api请求一起发送的json主体。

{
        "userId" : 7,
        "name": "test",
        "lastname": "testlast",
        "email": "testtest@yahoo.com",
        "password": "test123",
        "lastActive": "04/05/21",
        "createdDate": "02/04/20",
        "institution": {
            "institutionId": 4
            },
       "roles": [
            {
                "roleId": 2
            }
        ],  
        "active": false,
        "blocked": true
    }

一切对我的用户来说都很好，有一个角色表记录被添加了userid=7和roleid=2，但是问题是表角色被更新了，字段name和description被删除了，被空值替换了。。。有什么想法吗