docs: @Override
  	protected void checkPrimitiveValidity() {
  		BusPrimitiveInvalidity invalidityReason = null;
  		if (this.itineraries.isEmpty()) {
  			invalidityReason = new BusPrimitiveInvalidity(
  					BusPrimitiveInvalidityType.NO_ITINERARY_IN_LINE,
  					null);
  		} else {
  			final Iterator<BusItinerary> iterator = this.itineraries.iterator();
  			BusItinerary itinerary;
  			while (iterator.hasNext() && invalidityReason == null) {
  				itinerary = iterator.next();
  				if (!itinerary.isValidPrimitive()) {
  					invalidityReason = new BusPrimitiveInvalidity(
  							BusPrimitiveInvalidityType.INVALID_ITINERARY_IN_LINE,
  							itinerary.getName());
  				}
  			}
  		}
  		setPrimitiveValidity(invalidityReason);
  	}