Get/Set the Object that event callbacks for this joint will be sent to. Care should be taken with any Object assigned as a callback target that isn't a Object as this assignment will not in itself keep the object alive and can be garbage collected. To avoid this, you should have at least a single reference to the object in your code. To remove the object assigned here, set the callback target to NULL. This includes the following events: A PhysicsEvents.JointThresholdEvent with call PhysicsCallbacks.IJointThresholdCallback.

public object callbackTarget { get; set; }