title: @OneToOne and @JoinColumn, auto delete null entity , doable?
body: <p>I have two Entities , with the following JPA annotations :</p>
  
  <pre><code>@Entity
  @Table(name = "Owner")
  public class Owner implements Serializable
  {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "id")
    private long id;
  
    @OneToOne(fetch=FetchType.EAGER , cascade=CascadeType.ALL)
    @JoinColumn(name="Data_id")
    private Data Data;  
  }
  
  @Entity
  @Table(name = "Data")
  public class Data implements Serializable
  {
    @Id
    private long id;
  }
  </code></pre>
  
  <p>Owner and Data has one-to-one mapping , the owning side is Owner.
  The problem occurs when I execute : <strong>owner.setData(null) ; ownerDao.update(owner)</strong> ;
  The "Owner" table's Data_id becomes null , that's correct.</p>
  
  <p>But the "Data" row is not deleted automatically.
  I have to write another DataDao , and another service layer to wrap the two actions ( ownerDao.update(owner) ; dataDao.delete(data); )</p>
  
  <p>Is it possible to make a data row automatically deleted when the owning Owner set it to null ?</p>