code: public String extractResource(XEvent event) {
  		XAttribute attribute = event.getAttributes().get(KEY_RESOURCE);
  		if (attribute == null) {
  			return null;
  		} else {
  			return ((XAttributeLiteral) attribute).getValue();
  		}
  	}
docs: Extracts the resource attribute string from an event.
  
  @param event
  Event to be queried.
  @return Resource string for the given event (may be <code>null</code> if
  not defined)