title: optional JAXB xml attribute while marshalling
body: <p>When I marshal java object using JAXB I am getting below xml element</p>
  
  <pre><code>&lt;error line="12" column="" message="test" /&gt;
  </code></pre>
  
  <p>But I want xml as below</p>
  
  <pre><code>&lt;error line="12" message="test" /&gt;
  </code></pre>
  
  <p>If column value is empty then I need to get the xml as shown above otherwise I need to get the column attribute in the element.</p>
  
  <p>Is there any way to get it?</p>