[RFE] Revocation Notification

[Mitchell Adair]

Is your feature request related to a problem? Please describe.
There are cases where it may be important to perform some kind of cleanup when a subscription gets revoked

Describe the solution you'd like
Fire a notification for a revocation of a subscription.'

• Fire the event with a flag in the arguments?
  • could cause some issues with creating a good generalized handler for different events
• Fire a generalized 'revocation' event?
  • could be tough to perform cleanup when having to figure out what cleanup to actually perform