@Entity
@DiscriminatorColumn()
public abstract class User{
 
  @OneToMany(mappedBy="id.user")
  private List<Langs> langs
}

@Entity
  public class Langs{
   @Id private LangId id;
  }
@Embedable
public class LangId{
   private int id;
   @ManyToOne @JoinColumn(name="user_id" , refere..="id")
   private User user;
}