User Story

As an Automation and Slack user, I would like to be able to customize the JSON payload generated by the "Send Slack Message" action because this would enable me to take advantage of Slack's advanced message formatting.

Context

You can add rich layouts in Slack messaging using custom JSON, as outlined here. However the Automation "Send Slack Message" action takes just a text box; there is no advanced JSON editor like there is for "Edit Issue".

If we could customize the JSON directly, I could craft an advanced layout which included relevant Jira data, making the resulting message more valuable to end-users.