code: public Date extractTimestamp(XEvent event) {
  		XAttributeTimestamp timestampAttribute = (XAttributeTimestamp) event
  				.getAttributes().get(KEY_TIMESTAMP);
  		if (timestampAttribute == null) {
  			return null;
  		} else {
  			return timestampAttribute.getValue();
  		}
  	}
docs: Extracts from a given event the timestamp.
  
  @param event
  Event to be queried.
  @return The timestamp of this event, as a Date object (may be
  <code>null</code> if not defined).