hasSpatialChange method
Returns true if the change between a and b is spatial (position/geometry).
Implementation
@override
bool hasSpatialChange(Marker oldItem, Marker newItem) {
if (oldItem.point != newItem.point) return true;
if (oldItem.width != newItem.width) return true;
if (oldItem.height != newItem.height) return true;
return false;
}