I would suggest to wait for the draft info beeing moved to stable given the warning added here: https://developer.github.com/v3/pulls/

Nothing in joomla/github supports preview APIs anyway (and from what I remember it's next to impossible to shove anything in to customize requests without just not using the package), so any changes have to wait for stable API implementations.

This seems to be in the hooks now. On a PR incoming event there's a draft boolean. And there's a ready_for_review event when it moves from draft to ready for review https://developer.github.com/v3/activity/events/types/#pullrequestevent

#1079 Stores stuffy to databases

Completed with #1080