private static final long serialVersionUID = -3009157732242241606L;
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private long id;

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

@Column(name = "password")
private String password;

@Column(name = "email")
private String email;

@OneToMany
private Set<Friendship> friends = new HashSet<>();

public User(){

}

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

    private static final long serialVersionUID = -3009157732242241606L;
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long id;

    @ManyToOne
    private User owner;

    @ManyToOne
    @MapsId("id")
    private User friend;

    public Friendship() {

    }

}