title: JAXB not creating class for empty xs:element tag
body: <p>I am migrating a project from jaxb 1.0 to 2.1. When generating classes from an xsd using jaxb 2.1 (via an ant xjc task), the generated classes are missing elements which don't have any content like this:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8" standalone="yes"?&gt;
  &lt;xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="unqualified"&gt;
  ....
  &lt;xs:element name="get-all-services-partners-request"/&gt;
  </code></pre>
  
  <p>However files <em>are</em> generated when the element does have content, like this:</p>
  
  <pre><code> &lt;xs:element name="catalog-full-service-request"&gt;
     &lt;xs:complexType&gt;
       &lt;xs:sequence&gt;
         &lt;xs:element name="service-id" type="xs:string" minOccurs="0"/&gt;
         &lt;xs:element name="log-id" type="xs:string" minOccurs="0"/&gt;
       &lt;/xs:sequence&gt;
     &lt;/xs:complexType&gt;
   &lt;/xs:element&gt;
  </code></pre>
  
  <p>Why would this be?  A previous set of generated classes (using jaxb 1.0) contain classes for all elements, not just those with content.</p>
  
  <p>How do I get jaxb to generate these missing classes?  I don't really have rights to change the xsd (but could do so if really necessary).</p>