I am not able to find out the issue while reading received json? How can I debug ?

I am not able to find out the issue while reading received json? How can I debug ?

 For UAT you may create a temporary public endpoint on websites like https://requestbin.com/, update your webhook endpoint on Digio Enterprise Dashboard (Profile section) and perform a transaction where webhook is triggered. These public endpoint show the received data (Headers and Body) in readable format. 

 Observe received headers and Body and fix the issue in your code