This was discussed in https://groups.google.com/a/opencast.org/forum/#!topic/dev/4v5GmJDxuUc and all the requests/ideas were noted in MH-12231.
I am creating a separate ticket to address the specific case of resuming/aborting a workflow that is paused by the retry-strategy="hold" mechanism, which I am working on for DCE.
Hey [rute_santos], did you make any progress on this as we have a requirement to also pause, resume|abort running workflows?
duh, I've just seen the PR! I guess you could close this ticket