title: JAXB returns null for attributes with a namespace
body: <p>I need to unmarshall an XML that has namespaces for the attributes, for instance  </p>
  
  <pre><code>&lt;license license-type="open-access" xlink:href="http://creativecommons.org/licenses/by/2.0/uk/"&gt;&lt;license-p&gt;
  </code></pre>
  
  <p>This attribute is defined as  </p>
  
  <pre><code>@XmlAttribute(namespace = "http://www.w3.org/TR/xlink/")  
  @XmlSchemaType(name = "anySimpleType")  
  protected String href;  
  </code></pre>
  
  <p>But when I try to retrieve the href, it is null. What should I add/modify to the jaxb code in order to get the right value? I already tried to avoid namespaces but it did not work, still null. I also tried with <code>@XmlAttribute(namespace = "http://www.w3.org/TR/xlink/", name = "href")</code> but it did not work either. </p>
  
  <p>The top of the XML file is:</p>
  
  <pre><code>&lt;DOCTYPE article
    PUBLIC "-//NLM//DTD v3.0 20080202//EN" "archive.dtd"&gt;
  &lt;article xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:mml="http://www.w3.org/1998/Math/MathML" article-type="article"&gt;
  </code></pre>