title: How to add an XML namespace (xmlns) when serializing an object to XML
body: <p>I'm serializing Objects to XML with the help of XStream.
  How do I tell XStream to insert an xmlns to the XML output of my object? </p>
  
  <p>As an example, I have this simple object I want to serialize:</p>
  
  <pre><code>@XStreamAlias(value="domain")
  public class Domain
  {
      @XStreamAsAttribute
      private String type;
  
      private String os;
  
      (...)
  }
  </code></pre>
  
  <p>How do I achieve <em>exactly</em> the following output with XStream?</p>
  
  <pre><code>&lt;domain type="kvm" xmlns:qemu="http://libvirt.org/schemas/domain/qemu/1.0"&gt;
    &lt;os&gt;linux&lt;/os&gt;
  &lt;/domain&gt;
  </code></pre>