title: custom converter with xstream
body: <p>I need a custom convertor for my class Scope:</p>
  
  <pre><code>class Scope {
      private final String name;
      private final SomeProp prop;
      private final Item[] items;
      //...
  }
  </code></pre>
  
  <p>I registered my converter for SomeProp. But I want to use default converter for Item (and all sub-classes).</p>
  
  <p>How I can do it?</p>
  
  <p>I tried to override marshal/unmarshal:</p>
  
  <pre><code>public void marshal(Object val, HierarchicalStreamWriter writer, 
            MarshallingContext context) {
      //... saving name and prop
      writer.startNode("items");
  
      ArrayConverter conv = new ArrayConverter(mapper);
      assert(conv.canConvert(items.members.getClass()));
      conv.marshal(items.members, writer, context);
  
      writer.endNode);
  }
  
  public Object unmarshal(HierarchicalStreamReader reader,
      UnmarshallingContext context) {
      //... reading name and prop
      reader.moveDown();
  
      assert("items".equals(reader.getNodeName()));
  
      ArrayConverter conv = new ArrayConverter(mapper);
      Item[] items = (Item[])conv.unmarshal(reader, context);
      //...
  }
  </code></pre>
  
  <p>but by some reason unmarshal is not working.</p>