Parking randomly in Anylogic

I am using AnyLogic's Traffic Road Library and I know it's possible in the car Source module to define the initial position of the car in a parking lot. I want the parking lot space to be randomly chosen. I know there exists this function randomFreeSpaceIndex() that returns the index of randomly chosen free parking space. But I do not know how to call it on my car source or use it with the CarMoveTo tool. Here is my model so far https://cloud.anylogic.com/#/model/eb9dc1a2-e7df-4c01-a1a2-6e32581794e6;mode=SETTINGS

Any help is appreciated!