As part of ros-navigation/navigation2#3885, we're interested in representing footprints as polygons and storing them to do collision monitoring with respect to for multi-robot fleets.

Managing the N polygons and new incoming messages is complicated by the fact that the standard Polygon message has no form of unique ID field (int, uuid, etc) to identify one physical object instance being represented at t=T.

I would like to propose adding to PolygonStamped and potentially Polygon a uint16 id field as http://docs.ros.org/en/noetic/api/visualization_msgs/html/msg/Marker.html and others have themselves for similar deconfliction of unique objects.