Summary

Notifications to Slack aren't being triggered when custom events are associated with workflow steps.

Steps to Reproduce

1. Create a custom event as detailed on this documentation page: Adding a custom event
2. Edit a transition to trigger the custom event, rather than the Generic Event, as follows:

   Fire a <your custom Event here> event that can be processed by the listeners. 
   

3. Setup the Slack integration to fire when an issue is transitioned to the workflow transition associated with the custom event
4. Transition the issue
5. A notification will not be received in Slack

Expected Results

Custom events should be triggering a notification to Slack just like system events.

Actual Results

Workflow steps associated with custom events are not triggering a notification to Slack.

Workaround

The only workaround available is to setup the post function to use a system event, but this could have a negative impact (limit functionality) on the notification scheme if it's based on custom events.