code: public Map<List<String>, String> extractNestedDrivers(XEvent event) {
  		return XCostDriver.instance().extractNestedValues(event);
  	}
docs: Retrieves a map containing all cost drivers for all descending attributes
  of an event.
  
  @see #extractNestedDrivers(XEvent)
  
  @param event
  Event to retrieve all cost drivers for.
  @return Map from all descending keys to cost drivers.