Adding options to widget created via API call

TL;DR: Where can I find documentation on what options I can pass to the createWidget function in the javascript (non node.js) SDK to set up advanced options, like a callback url.

Hello, I am trying to implement a waiver signing feature to my application. I have determined that a widget is exactly what I need to accomplish this. However, I have a couple of problems:

When I create a widget manually via the Adobe sign dashboard, I cannot seem to set more advanced options, namely a call back URL for the form to return to when the user has completed the form.

To remedy this, I figure I will have to use the API (though, I think its absolutely ridiculous that I can't set these options in the dashboard) and I have successfully added code that will create a new widget, using the createwidget sample from the sdk. I am using the Javascript (NOT node.js) browser based API by the way.

So, my problem now is that, like when I created the widget manually via the dashboard, I can't set the option for the callback URL (Or any options for that matter), simply because I don't know what the options are called, or what their values should be. I have searched and searched, including these forums, google, and the API documentation (which isn't as comprehensive as I would have liked) but I cannot seem to find any page or information on what specific options you can use, what they are called, and what values they can have.

I HAVE read the documentation regarding the createWidget function, which is what I am using, and I did indeed confirm that the function DOES allow for passing an option parameter. However, the documentation has absolutely no information, from what I have been able to find, on how these options work, what they are, and what values they can have.

So I'm basically left trying to randomly guess what the options could be, which is obviously not an optimal solution.

If anyone could detail what these options are, or at the very least what the option I need for setting the callback URL that would be appreciated. Even better, however, would be if someone could point me to a page in the documentation or elsewhere that details what exactly the options can be, their possible values, and optimally the format with which they must be sent (I assume some sort of json object).

Thanks in advance for any answers I get.