@Embeddable
public class ContactKey implements Serializable {

  /**
   * eclipse generated
   */
  private static final long serialVersionUID = 3787146968072373925L;

  /**
   * @TODO Entity: needs to replace the temp sequence
   */

  @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "test_seq")
  @SequenceGenerator(name = "test_seq", sequenceName = "test_s", allocationSize=1)
  @Column(name="CNTCT_ID")
  private Integer id;
 
  @ManyToOne(fetch=FetchType.EAGER)
  @JoinColumn(name="CLNT_ID")
  private Client client;

.....
On the Contact class side:

@Entity
@Table(name="CNTCT")
public class Contact {


  @EmbeddedId
  private ContactKey key;
 

.....
On the Client class side:

@Entity
@Table(name="CLNT")
public class Client {
 

  @Id
  @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "test_seq")
  @SequenceGenerator(name = "test_seq", sequenceName = "test_s", allocationSize=1)
  @Column(name="CLNT_ID")
  private Integer id;

  @OneToMany(cascade=CascadeType.ALL, fetch=FetchType.EAGER, mappedBy="key.client")
  private Set<Contact> contacts;

......
On the Test class:


    Client client = new Client();

    Contact contact = new Contact();
    contact.setClient(client);
    client.addContact(contact);

then save