title: JAXB required=true doesn't seem to require
body: <p>We have this JAXB annotation:</p>
  
  <pre><code> @XmlElement(name = "Strategy", required = true)
   protected List&lt;Strategy&gt; strategy;
  </code></pre>
  
  <p>If there are no <code>Strategy</code> elements present, no exception is thrown..  why is this?  Shouldn't we get an exception?</p>