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

    @Id
    private String user_name;
    @Id
    private String role_name;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "user_name", referencedColumnName = "name")
    private User user;

    ...
}

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

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;
    private String name;
    private Date created_at;
    private Date updated_at;


    @OneToMany(mappedBy = "user")
    public List<Role> roles;

   ...
}

        CriteriaBuilder cb = entityManager.getCriteriaBuilder();
        CriteriaQuery<User> cq = cb.createQuery(User.class);
        Root<User> rootUser = cq.from(User.class);
        cq.where(cb.equal(rootUser.get(User_.name), "admin"));
        TypedQuery<User> query = entityManager.createQuery(cq);
        User user = query.getSingleResult();

        log(user.getName());
        for (Role role : user.roles)
            log(role.getRole_name().toString());

22:13:23,152 INFO  [org.hibernate.hql.internal.QueryTranslatorFactoryInitiator] (default task-28) HHH000397: Using ASTQueryTranslatorFactory
22:13:23,155 INFO  [stdout] (default task-28) Hibernate: select user0_.id as id1_1_, user0_.created_at as created_2_1_, user0_.name as name3_1_, user0_.updated_at as updated_4_1_ from user user0_ where user0_.name=?
22:13:23,157 INFO  [io.undertow.servlet] (default task-28) com.mezoline.servlet.IndexServlet: admin
22:13:23,157 INFO  [stdout] (default task-28) Hibernate: select roles0_.user_name as user_nam1_0_0_, roles0_.role_name as role_nam2_0_0_, roles0_.user_name as user_nam1_0_1_, roles0_.role_name as role_nam2_0_1_ from role roles0_ where roles0_.user_name=?
22:13:23,161 INFO  [stdout] (default task-28) Hibernate: select user0_.id as id1_1_0_, user0_.created_at as created_2_1_0_, user0_.name as name3_1_0_, user0_.updated_at as updated_4_1_0_ from user user0_ where user0_.name=?
22:13:23,164 INFO  [stdout] (default task-28) Hibernate: select user0_.id as id1_1_0_, user0_.created_at as created_2_1_0_, user0_.name as name3_1_0_, user0_.updated_at as updated_4_1_0_ from user user0_ where user0_.name=?
22:13:23,165 INFO  [stdout] (default task-28) Hibernate: select user0_.id as id1_1_0_, user0_.created_at as created_2_1_0_, user0_.name as name3_1_0_, user0_.updated_at as updated_4_1_0_ from user user0_ where user0_.name=?
22:13:23,167 INFO  [io.undertow.servlet] (default task-28) com.mezoline.servlet.IndexServlet: ADMINISTRATOR
22:13:23,167 INFO  [io.undertow.servlet] (default task-28) com.mezoline.servlet.IndexServlet: USER
22:13:23,169 INFO  [io.undertow.servlet] (default task-28) com.mezoline.servlet.IndexServlet: TEST

    @OneToMany()
    @JoinColumn(name = "role_name", referencedColumnName = "name")
    public List<Role> roles;

22:17:32,568 INFO  [org.hibernate.hql.internal.QueryTranslatorFactoryInitiator] (default task-31) HHH000397: Using ASTQueryTranslatorFactory
22:17:32,571 INFO  [stdout] (default task-31) Hibernate: select user0_.id as id1_1_, user0_.created_at as created_2_1_, user0_.name as name3_1_, user0_.updated_at as updated_4_1_ from user user0_ where user0_.name=?
22:17:32,573 INFO  [io.undertow.servlet] (default task-31) com.mezoline.servlet.IndexServlet: admin
22:17:32,573 INFO  [stdout] (default task-31) Hibernate: select roles0_.role_name as role_nam2_0_0_, roles0_.user_name as user_nam1_0_0_, roles0_.user_name as user_nam1_0_1_, roles0_.role_name as role_nam2_0_1_ from role roles0_ where roles0_.role_name=?

 user_name	role_name 
admin	ADMINISTRATOR
admin	USER
admin	TEST

    @OneToMany()
    @JoinColumn(name = "role_name", referencedColumnName = "name")
    public List<Role> roles;

    @OneToMany()
    @JoinColumn(name = "user_name", referencedColumnName = "name")
    private List<Role> roles;