title: java.lang.IllegalArgumentException: local part cannot be "null" when creating a QName
body: <p>I'm trying to add following xml to my soap body after converting it to document</p>
  
  <pre><code>&lt;ns2:OSSRequest xmlns:ns2="http://www.someurl"&gt;
  &lt;requestBody&gt;
      &lt;property&gt;
          &lt;address&gt;
              &lt;addressId&gt;someValue&lt;/addressId&gt;
              &lt;municipality&gt;someValue&lt;/municipality&gt;
              &lt;postalCode&gt;someValue&lt;/postalCode&gt;
              &lt;province&gt;someValue&lt;/province&gt;
              &lt;streetNumber&gt;someValue&lt;/streetNumber&gt;
          &lt;/address&gt;
      &lt;/property&gt;
      &lt;requestedProducts&gt;
          &lt;products&gt;someValue&lt;/products&gt;
          &lt;products&gt;someValue&lt;/products&gt;
      &lt;/requestedProducts&gt;
  &lt;/requestBody&gt;
  &lt;requestHeader/&gt;
  </code></pre>
  
  <p></p>
  
  <p>but I'm getting error </p>
  
  <pre><code>java.lang.IllegalArgumentException: local part cannot be "null" when creating a QName
  </code></pre>
  
  <p>here is the code I'm using for converting xml to soap body</p>
  
  <pre><code>MessageFactory factory = MessageFactory.newInstance();
  SOAPMessage message = factory.createMessage();
  SOAPHeader header_soap = message.getSOAPHeader();
  SOAPBody body = message.getSOAPBody();
  Document document = convertStringToDocument(xml);
  body.addDocument(document); // getting error on this line
  </code></pre>
  
  <p>following is the code which is converting xml to document</p>
  
  <pre><code>private Document convertStringToDocument(String xmlStr) {
      DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
      DocumentBuilder builder;
      try {
          builder = factory.newDocumentBuilder();
          Document doc = builder.parse(new InputSource(new StringReader(xmlStr)));
          return doc;
      } catch (Exception e) {
          e.printStackTrace();
      }
      return null;
  }
  </code></pre>
  
  <p>Is my xml invalid ? Or I'm missing any configs while adding it to document ?    </p>