When an Attached Collision Object is removed, it should actually be removed

[AndyZe]

From issue #1069 , I learned that specifying moveit_msgs::AttachedCollisionObject::REMOVE of an Attached Collision Object does not actually remove it. It just converts it to a non-attached collision object.

I think specifying REMOVE should actually make the object disappear like it does for a regular collision object.

Maybe an additional DETACH message field would be a good idea, in case detachment is the goal.

Some relevant code is in planning_scene.cpp processAttachedCollisionObjectMsg(). Here is the message type: http://docs.ros.org/en/noetic/api/moveit_msgs/html/msg/AttachedCollisionObject.html

[v4hn]

This is the failed design in MoveIt where it was much too late to change it... It's perfectly justified to finally clean this up in MoveIt2 and cleanly provide ATTACH/DETACH!

Changing the meaning of REMOVE in attached objects without indication is a severe issue though and users will wonder where their objects went after detach with their existing code. It might be a very good idea to change the command names/values altogether to make sure user code that relies on this behavior breaks.