v1.3.5 of UPS/OAuth-RESTful is now available for download: https://www.zen-cart.com/downloads.php?do=file&id=2374

This release removes the string type-hints from the API class' function, enabling the shipping module to be used without edits on sites still running PHP 5.6.

Those sites really, really need to be upgraded but given that the UPS-XML method's going to disappear in a week, I'm giving them a break.