title: JPA EclipseLink @OneToMany returns empty set
body: <p>I am using an embedded id:</p>
  
  <pre><code>@Embeddable
  public class EntityId {
      private long id;
  }
  </code></pre>
  
  <p>And I have the following tables:</p>
  
  <pre><code>@Entity
  public class Master {
      @EmbeddedId private EntityId id;
  
      @OneToMany(mappedBy = "master")
      Set&lt;Config&gt; configs;
  }
  
  @Entity
  public class SlaveLeft {
      private @EmbeddedId EntityId id;
  }
  
  @Entity
  public class SlaveRight {
      private @EmbeddedId EntityId id;
  }
  
  @Entity
  public class Config {
  
      @EmbeddedId private EntityId id;
  
      @ManyToOne
      @JoinColumn(name = "MASTER_ID", referencedColumnName = "id")
      private Master master;
      @ManyToOne
      @JoinColumn(name = "LEFT_ID", referencedColumnName = "id")
      private SlaveLeft slaveLeft;
      @ManyToOne
      @JoinColumn(name = "RIGHT_ID", referencedColumnName = "id")
      private SlaveRight slaveRight;
  }
  </code></pre>
  
  <p>I then populate the database:</p>
  
  <pre><code>    final EntityManager em = injector.getInstance(EntityManager.class);
      em.getTransaction().begin();
      Master master = new Master(EntityId.next());
      SlaveLeft slaveLeft = new SlaveLeft(EntityId.next());
      SlaveRight slaveRight = new SlaveRight(EntityId.next());
      Config config = new Config(EntityId.next(), master, slaveLeft, slaveRight);
  
      em.persist(master);
      em.persist(slaveLeft);
      em.persist(slaveRight);
      em.persist(config);
      em.getTransaction().commit();
  
      final Master master1 = em.find(Master.class, master.getId());
      System.out.println(master1.getConfigs());
  </code></pre>
  
  <p>The problem is that the master1.getConfigs() returns empty.</p>
  
  <p>What am I missing to get a working relation?</p>