KevinTheJedi There is, but within that folder, it looks like the phar is already unpacked.
I went ahead and just copied the changes to the existing oauth2.php, no db modifications, and reran the token refresh. No error, and I just got the ticket generations. As far as I can immediately tell, your changes worked.
EDIT: for reference, we're on 1.17.2, using a custom domain within Exchange Online (no outlook.com or onmicrosoft.com)