title: Java EntityManager merge and @PrePersist
body: <p>I use this piece of line to merge:</p>
  
  <pre><code>partner = em.merge(partner);
  </code></pre>
  
  <p>and this is in my entity:</p>
  
  <pre><code>@PrePersist
  public void updateModificationDate(){
      this.lastModificationDate = new Date();
  }
  </code></pre>
  
  <p>So as you can see, I want to keep up when the entity was last changed,</p>
  
  <p>but the method never gets called,</p>
  
  <p>Anybody an idea of what I could do?</p>