Handle on a marker previously created through IMapAdapter.createMarker(),
returned by IMapAdapter.getMarkerHandle().
Deliberately narrow: id-based management stays the rule, and this handle exists
only for the interactions the id-based surface cannot express — reading a marker's
live position after the user has dragged it, and subscribing to its own events.
It is typed rather than opaque so callers need no cast; keep it minimal, and add a
member only when a real consumer needs one.
Handle on a marker previously created through
IMapAdapter.createMarker(), returned byIMapAdapter.getMarkerHandle().Deliberately narrow: id-based management stays the rule, and this handle exists only for the interactions the id-based surface cannot express — reading a marker's live position after the user has dragged it, and subscribing to its own events. It is typed rather than opaque so callers need no cast; keep it minimal, and add a member only when a real consumer needs one.