Managing multiple AdWords accounts for customers and linking each with corresponding GBM account

[kru...@yclub.io]

Hello, 

I was reading up on the AdWords API guides and saw that I need a refresh token created for the AdWords account which I am trying to link with Google My Business.

I plan to have customers who have already registered GMB and provide them with AdWords automation service.

For now, it seems to me that I will need to acquire that refresh token completely programmatically.

I am starting with the Java client library and have gotten my refresh_token via copy, pasting some code I got from a Google page.

This I think will require me to tinker around with the library code and then using some sort of HeadlessWebDriver to sign-in and copy the code.
This will also require me to ask my customers their gmail and password which I would rather avoid if possible.

How would you fellow devs approach this problem?