self close tag issue xstream when null
===

I have an class like below and I use xSteam to convert Edge to xml.
    
    @XStreamAlias("edge")
    class Edge{
        
         @XStreamAsAttribute
         @XStreamAlias("source")
         private String source;
       
         @XStreamAsAttribute
         @XStreamAlias("target")
         private String target;
         
         @XStreamAlias("data")
         private Data data;
         .....
    }


When I set data=null, i can get 

      <edge source="8" target="10" />
   
but I want to get below when data =null

      <edge source="8" target="10" ></edge>

Some one can help for this?
