Is there a ScriptRunner API for interacting with approvals in JIRA Service Desk?

[Huyen Huynh]

I'm trying to use automation to automatically update a custom field after an approval button is pressed.

I was unable to determine how to get scriptrunner to be invoked using a post function on a transition since "approved" does appear to be a transition (if there are multiple approvers).

I'm currently trying to use an 'after edit' action in the 'Automation for Jira' plugin, but I can't find any documentation on how to interact with the Approver custom field / object in scriptrunner to move forward.  The only references I've found on the internet is this link:

https://community.atlassian.com/t5/Adaptavist-questions/Scriptrunner-How-to-list-approvers/qaq-p/793699

But when I try to use that, I run into static type errors trying to call 'getApprovals()' on an object.  Are there API docs that I'm not finding?

My JIRA version is 8.5.3.