code: public XEventClass getByIndex(int index) {
  		for (XEventClass eventClass : classMap.values()) {
  			if (eventClass.getIndex() == index) {
  				return eventClass;
  			}
  		}
  		return null;
  	}
docs: Returns a given event class by its unique index.
  
  @param index
  Unique index of the requested event class.
  @return The requested event class. If no matching event class is found,
  this method may return <code>null</code>.