This is a really interesting approach to try enable the ability to view the content of the https request being made, but it is worth noting that mitmproxy routinely triggers antivirus software, and therefore might not be a viable option for many.

I instead had to opt for throwing together a quick and dirty nodeJS app to get eyes on the output of the EnsLib.HL7.Operation.HTTPOperation to understand why I was hitting a snag with a supplier. Turns out the content-type from this operation is text/html and the supplier was expecting  text/plain...

Well, this has got me ordering the hardware already!

I can't wait to get my hands on the repo, and look forward to the inevitable battle with our security team (which, to be fair, would be within their rights to be concerned).