spring-vaadin three tables joined

I have three tables, Groupauthorities,Roles and Groups.
Groupauthorities has three columns eg. id, role_id and group_id.
Roles also has two columns eg. id, rolename_x and groups also has two columns eg. id, groupname_x
Groupauthorities has many-to-one relationship with roles and groups. The groupauthorities must show in vaadin table as below
ID Roles Name Group Name
1 ROLE_ADMIN Administrators
2 ROLE_USER Administrators

I googled for the solution how to use spring-data-jpa with many tables joined together and I found it as below
public interface MyRepository extends JpaRepository {
String sql = "SELECT t1.id as id, t2.role_x as roleX, t3.groupname_x as groupnameX " +
"FROM group_authorities as t1, roles as t2, groups as t3 " +
"WHERE t2.id = t1.role_id " +
“AND t3.id = t1.group_id”;
@Query(name = sql, nativeQuery = true)
List<Object> methodThatQueriesMultipleTables();
I use BeanItemContainer to load from the database to vaadin table. However, if I use this one as below, it would reject as it needs one class.
BeanItemContainer groupauthoritiesContainer = new BeanItemContainer<>(
GroupAuthorities.class, Roles.class, Groups.class
The only one thing I can think of is using Vaadin SQLContainer addon. Remember I use Vaadin Spring addon. It will work with these two addons.

I am not happy with these addons together as I like to keep the codes clean and easy to look at.

What is the solution of using BeanItemContainer or others?

Looking foward to hearing from you.

I want to inform you that the problem is solved.

You just overwrite the toString() in the domain/model class.

For example,
@Table(name = “groups”)
public class Groups extends AbstractEntity {

@Column(name = "groupname_x")
private String groupnameX;

@OneToMany(mappedBy = "groupsByGroupId")
private Collection<GroupAuthorities> groupAuthoritiesById;

@OneToMany(mappedBy = "groupsByGroupId")
private Collection<GroupMembers> groupMembersesById;

public Groups() {}

public Groups(String groupnameX, Long userChanged) {
    this.groupnameX = groupnameX;
    this.userChanged = userChanged;


public String toString() {
return id + “,” + groupnameX;