title: JPA fetch on 3 levels
body: <p>I need to do something like that :</p>
  
  <p>The structure is : </p>
  
  <p>X contains a list of Y. 
  Y contains or not a list of Z.</p>
  
  <pre><code>Xroot.fetch("Y", JoinType.INNER);
  Xroot.fetch("Y.Z", JoinType.LEFT);
  </code></pre>
  
  <p>But in JPA the last line does not work. Any ideas how to do it ?</p>