Display the marker only if it does not overlap with other markers. If two markers of this type would overlap, the one with the higher zIndex is shown. If they have the same zIndex, the one with the lower vertical screen position is shown.
Always display the marker regardless of collision. This is the default behavior.
Always display the marker regardless of collision, and hide any OPTIONAL_AND_HIDES_LOWER_PRIORITY markers or labels that would overlap with the marker.
The CollisionBehaviour enum is copied from Google Maps typings in order to allow those to be used before the api has loaded.