When you are working with SAP CPI it is often a good idea to understand what kind of HTTP request is being sent and what you are getting back.
I have used some different mocking/logging services over my time. I used requestbin.fullcontact.com/ but it has not been so stable. The last service I got to try was https://www.mockable.io
The cool thing about mockable is that it enables users to set up sample responses to requests. So if your CPI flow requires a specific response or header you can set it.
There is a free version and the premium version is just 12USD/month.
I have created a short demo video of it here.