title: java.util.ConcurrentModificationException on CollectionOfElements
body: <p>I seem to get a ConcurrentModificationException when I have a CollectionOfElements inside an Embedabble.</p>
  
  <p>If would like to have it like that, however If I change Route from Embedabble's to Entity than everything works fine. I have even tried adding @Version, but that doesn't seem to work.</p>
  
  <p>Here are a snippet of my classes.
  Kart.java:</p>
  
  <pre><code>@Entity
  public class Kart {
  
  @Id @GeneratedValue
  private Long id;
  
  @Column(nullable=false,length=256)
  @NotNull
  @Length(max=256)
  private String name;
  
  @OneToOne(cascade=CascadeType.ALL)
  private File file;
  
  @Version
  private int version;
  
  @CollectionOfElements
  private Set&lt;Route&gt; route;
  </code></pre>
  
  <p>Route.java:</p>
  
  <pre><code>@Embeddable
  public class Route {
  
  @Parent
  private Kart kart;
  
  @NotNull
  @Column(nullable = false, length = 256)
  private String name;
  
  @NotNull
  @Column(nullable = false)
  private Boolean visible = Boolean.valueOf(true);
  
  @CollectionOfElements
  private Set&lt;Coordinates&gt; coordinates;
  
  @Version
  private int version;
  </code></pre>
  
  <p>Coordinates.java:</p>
  
  <pre><code>@Embeddable
  public class Coordinates {
  
  @NotNull
  private int x;
  
  @NotNull
  private int y;
  
  @Parent
  private Route route;
  
  @Version
  private int version;
  </code></pre>
  
  <p><b>I have generated Hashcode/equals for Coordinates and Route</b></p>