Lost id attributes with nested implicit collections

ID attributes get lost outside an element. See the following testcase.

import com.thoughtworks.xstream.XStream; import com.thoughtworks.xstream.io.xml.DomDriver;
import java.util.ArrayList;

public class Bug {
public static void main(String[] args)

{ final List another = new List(); another.o = new Object(); another.list.add(new Object()); final XStream x = new XStream(new DomDriver()); x.setMode(XStream.ID_REFERENCES); x.addImplicitCollection(List.class, "list"); System.out.println(x.toXML(another)); }

}

class List {
public Object o;
public ArrayList list = new ArrayList();
}