Custom drop down list populated with AD users

Per Löfgren_plpgtu

We are using request types in JSM for onboarding, offboarding and users change. 
The user picker list for offboarding and user change is only populated with active users.
This is as expected and a good behavior by design.
Problem is that when a user is disabled due to account expire date or he or she is back from leave the list user is not visible in the list. 
Workaround is to create a customer but then that user is not provisioned from AD and not a good solution.

We dont want changes to be made in AD without a request type filled out.
Is there any tool out there that can populate a custom list with users from a AD or AAD. 

Nic Brough -Adaptavist-

I don't think there's a way to do this on Cloud at the moment, I can't find an app that can do it.  There are a couple which can read attributes from a directory but they don't provide custom picker fields.

That suggests that it should be possible to write an app to do it.

A second option might be to have an external script do a sync.  Create a select-list custom field, and then have a script which reads your directory, looks for new people, and adds them to the list over Jira's REST API (you wouldn't want to delete options obviously)