How do I get systemAttribute.taskId in form.

Summary

How do I get systemAttribute.taskId in form.

Content

I built an integration for the /bpm/tasks/{id}/attachments endpoint.  Then, when one of my forms loads, I populate a table with the results.  Basically its a table where users can select the task's attachments and click a button whcih then calls a web service on a different server the grabs those attachments and uploads them to a different server altogether.  I have it working completely except I can't figure out how to get the taskId on the webform.