code: public void marshal(Object obj, HierarchicalStreamWriter writer,
  			MarshallingContext context) {
  		XEvent event = (XEvent) obj;
  		writer.addAttribute("xid", event.getID().toString());
  		if (event.getAttributes().size() > 0) {
  			writer.startNode("XAttributeMap");
  			context.convertAnother(event.getAttributes(), XesXStreamPersistency.attributeMapConverter);
  			writer.endNode();
  		}
  
  	}
docs: /*
  (non-Javadoc)
  
  @see
  com.thoughtworks.xstream.converters.Converter#marshal(java.lang.Object,
  com.thoughtworks.xstream.io.HierarchicalStreamWriter,
  com.thoughtworks.xstream.converters.MarshallingContext)