title: XStream deserialization when variable type changed
body: <p>I have a java class that looks like</p>
  
  <pre><code>public class MyClass {
     private final String str;
     private Polygon polygon; // this polygon is a custom type of mine
  }
  </code></pre>
  
  <p>I have an xml file that has an instance of <code>MyClass</code> written to it using XStream.</p>
  
  <p>Now <code>MyClass</code> has changed and polygon has been replaced with <code>List&lt;Polygon&gt;</code> and the field has been renamed to <code>polygons</code>, and I'm trying not to break deserialization. I want to change the deserialization of the <code>polygon</code> field to basically read the polygon and then just create a new list and add the single polygon to it. The list would then be the new field value.</p>
  
  <p>Is it possible to change the conversion of just this one field? Or do I need to write a custom converter for the whole class <code>MyClass</code>?</p>
  
  <p>thanks,
  Jeff</p>