I've recently coded a few Drupal\x\Plugin\Action classes that respond nicely to my VBO (now bulk actions?) in Drupal 8. Now I'd like to implement a hook, or whatever is required, to take action when all the entities in a selected action have been processed...essentially a VBO post-process hook like we had with hook_views_bulk_operations_finish in Drupal 6. Where and how can I implement that?
I see no obvious hook in D8 to do this, and unfortunately, I've been unable to get Rules to work in D8 (still really confused by Rules and Actions configuration) so I really don't want to go down that path if I don't have to, yet.