title: jaxb marshaller remove unused namespace
body: <p>I'm using jaxb to marshall data </p>
  
  <pre><code>@XmlAccessorType(XmlAccessType.FIELD)
  @XmlType(name = "MessageType", propOrder = {
  
  })
  @XmlRootElement(name = "message")
  
    protected String source;
    protected GroupesVeh groupesVeh;
    @XmlSchemaType(name = "dateTime")
    protected XMLGregorianCalendar heureMesure1;
    @XmlSchemaType(name = "dateTime")
    protected XMLGregorianCalendar heureMesure2;
  </code></pre>
  
  <p>and when i m using jaxb to marshal this like :</p>
  
  <pre><code>  Marshaller marshaller = jaxbContext.createMarshaller();
    marshaller.marshal(messageType, writer);
  </code></pre>
  
  <p>i got :</p>
  
  <pre><code>&lt;source xmlns="" xmlns:ns7="http://www.w3.org/2005/08/addressing"&gt;SOURCE&lt;/source&gt;
  &lt;groupesVeh xmlns="" xmlns:ns7="http://www.w3.org/2005/08/addressing"/&gt;
  &lt;heuremesure1 xmlns="" xmlns:ns7="http://www.w3.org/2005/08/addressing"&gt;2016-02-12T14:40:56.000Z&lt;/heuremesure1&gt;
  &lt;heuremesure2 xmlns="" xmlns:ns7="http://www.w3.org/2005/08/addressing"&gt;2018-02-07T10:59:00.439Z&lt;/heuremesure2&gt;
  </code></pre>
  
  <p>how can i do to remove xmlns="" xmlns:ns7="http://www.w3.org/2005/08/addressing"? to obtain only :</p>
  
  <pre><code>    &lt;source&gt;SOURCE&lt;/source&gt;
      &lt;groupesVeh/&gt;
      &lt;heureMesure1&gt;2016-02-12T14:40:56.000Z&lt;/heureMesure1&gt;
      &lt;heureMesure2&gt;2018-02-07T09:21:48.092Z&lt;/heureMesure2&gt;
  </code></pre>
  
  <p>thanks by advance.</p>