Please add method which return waypointIndex.

We have Setter there but Getter is missing.

Getter will be useful in situation when you have group of NPC with leader - he know all waypoints and members mainatining formation based on position and orientation of leader.
When Leader die, one of members will get his role and need know to which waypoint from wayponts array he should go to (int GetCurrentWaypoint() from dead leader) and then new leader will set that waypoint
using SetCurrentWaypoint(int waypointIndex)

Please consider also ticket T166175 where I am recommending that those waypoints will be useful for others AI templates like Predators or even Zombie AI template.