Jira duplicates mentioned notifications when the project has an empty event in the Notification Scheme

Summary

When the project has a notification scheme where at least one event has no recipients configured the mentioned notifications may be duplicated or triplicated.

What happens is that Jira will generate one mentioned notification for each action performed.

• If you add a comment mentioning someone - Jira generates only one notification
• If you transition the issue and during the transition, you add a comment - Jira generates 2 notifications
• If you transition the issue and during the transition, you add a comment and edit a field - Jira generates 3 notifications

All notification will be the same

xxxx mentioned you on xxx-1

Customer Impact

Environment

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Steps to Reproduce

1. Create a new notification scheme, don't add any recipients, let it empty
2. Go to a project and associate the empty notification scheme to this project
3. Edit the workflow in this project and add screens to the transitions
4. Create a new issue in this project
5. Perform a transition and, in the transition screen, add a comment mentioning someone and edit a field.

Expected Results

Jira should generate only one mentioned notification

Actual Results

Jira generates 3 mentioned notification to the mentioned user

Application logs:

Notes

This behavior is also noticed even if the notification scheme has at least one event without a recipient.

Workaround

Edit the notification scheme adding a single email as a recipient to the events, it can be a dummy email.
Note: The problem persists if the Project Lead is used as a recipient of the notifications, it's necessary to choose any other recipient in its place.