The idea of the unfinished implementation of the feature "Participation Management" was to create scheduled events for all lectures that take place assuming all lectures will be recorded except if a person explicitly asks for not being recorded (Opt-out model).
Opencast would than track the "Opt-out" status for scheduled events and not record scheduled events in status "opt-out".
Additionally, there seems to be some kind of mechanism that likely was supposed to manage the opt-out directly in Openecast. This uses "review status" (UNSENT, UNCONFIRMED, CONFIRMED) and "review date" together with a bulk message facilities (sending e-mails).
The implementation of this feature was never completed.
The goal of this task is to remove all code related to this unfinished feature from the Opencast codebase.