title: Retain Project Structure[element order] while writing pom file using MavenXpp3Writer
body: <p>In my usecase I need to update values certain project properties in pom file, at run time.
  Hence the code  I use is like this.</p>
  
  <pre><code>MavenXpp3Reader reader = new MavenXpp3Reader();
  pomStream = new FileInputStream(pomF);
  Model model = reader.read(pomStream);
  
         // update properties 
  
    model.setProperties(modelProperties);
    MavenXpp3Writer writer = new MavenXpp3Writer();
    writer.write(new FileWriter(pomF), model);
  </code></pre>
  
  <p>When I do this the elements of pom file are completely re arranged. I need to retain the structure and simply update properties as I need to perform git commit of changed file.</p>
  
  <p>Is there a way to achieve this.?</p>