POST method fails with 404 (Bad Request)

[praveenkrjha]

Thanks Jonathan for posting a workaround for iOS certificate pinning till HttpClient supports ServerCertificateValidationCallback with NSUrlSession.
I copied your example with NSUrlSessionHandler and certificate pinning works great. However, all the POST (or PostAsync) calls fails with 404 (Bad Request).
I checked server logs and found that the JSON post data is corrupted.

Did you observe the same? How do we fix it?