title: Criteria api Restriction of foreign key
body: <p>i'm using Hibernate criteria api in my java ee app. I have two Agenda interface in witch i use jsf/primefaces schedule. the first one get data with the method findall() but the second one get data with the method findByCriteria(cri). in the cri variable i have to compare a foreign key with null value
  like this:</p>
  
  <pre><code>Criterion cri= Restrictions.eq("demande",null);
  listIntervention=interventionService.findByCriteria(cri);
  </code></pre>
  
  <p>this syntax it doesn't work 
  can some one help me? thanks in advance</p>