Creating a Jira Automation Rule trigger for when a Pull request goes from draft to published and sending a slack message

Question

I'm working on setting up an Automation rule in Jira. In this rule, my aim is to create a trigger that activates when a pull request transitions from the "Draft" state to "Published" in Azure.

The ultimate goal is to send a notification to Slack when a pull request is published.

Currently, I've configured the trigger to activate when a pull request is created. I've also been trying to create a JQL query that checks if a pull request is published, but I haven't been successful with it.

However, I suspect that I'll need to create a custom trigger specifically for the event of a pull request being published, rather than when it's initially created.

I would appreciate any guidance on how to achieve this and what the appropriate JQL query or steps should be.