Failing to correctly group ArgoCD slack notifications with groupingKey

[tamillaumudova]

Checklist:

• [+] I've searched in the docs and FAQ for my answer: https://bit.ly/argocd-faq.
• [+] I've included steps to reproduce the bug.
• [+] I've pasted the output of argocd version.

Describe the bug

We want to group out slack notifications in the same thread when an automatic sync starts and succeeds/fails. Initially, I used the groupingKey "{{.app.status.sync.revision}}" (as well as this one "{{.app.status.operationState.syncResult.revision}}") specified in this doc, however, it wouldn't group the messages in the thread.

I also attempted to group them with groupingKey set to "{{.app.status.operationState.operation.id}}", {{.app.status.operationState.operation.revision}} which also did not work.

On top of this, I also tried to add a unique identifier of application name {{.app.metadata.name}} to the groupingKey such as "{{.app.metadata.name}}-{{.app.status.operationState.operation.revision}}" which also didn't help.

To Reproduce

This is our logic for sending out start, success and fail notifications (without groupingKey included)

- when: app.status.operationState != nil and app.status.operationState.phase in ['Running']
  description: Application is being synced
  send: [app-sync-running]
  oncePer: app.status.operationState.syncResult.revision

- when: app.status.operationState != nil and app.status.operationState.phase in ['Succeeded'] and app.status.health.status == 'Healthy'
  description: Application is synced and healthy. Triggered once per commit.
  # since dora metrics are currently in closed beta, this will not actually send anything until we're added to the beta, or it's GA
  send: [dora, app-sync-status]
  oncePer: app.status.operationState.syncResult.revision

- when: app.status.operationState != nil and app.status.operationState.phase in ['Error', 'Failed']
  description: Application syncing has failed
  send: [app-sync-failed]
  oncePer: app.status.operationState.syncResult.revision

Expected behavior

For an application, we have the slack messages for a sync operation (start + success or fail) being sent as a single thread

Screenshots

Version

Paste the output from `argocd version` here.
v2.11.2

Logs

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