Adaptive Payment SDK calls starting failing sometime in Q4 2020

[gbatchvarov]

I am using PayPal Adaptive Payments Java SDK version 2.9.117. It had been working fine for couple of years and all of a sudden sometime in Q4 2020 the payment request calls started failing with Error ID: 580028 Malformed URL for the cancelUrl. Here is the URL:

https://www.example.com/order/cancelPayment?payKey=${payKey}