Microsoft Learn - Xamarin + Twilio

I ran through "Share your location as a text message using Azure Functions and Twilio" at Microsoft Learn to understand Xamarin. It looks not just about Xamarin, and you cannot learn the whole picture of Xamarin from this, but it is a good practice if you are not familiar with client apps.They system figure is below.

HttpRequest and HttpRequestMessage for Azure Functions

I was working on Microsoft Learn, "Share your location as a text message using Azure Functions and Twilio", and faced a problem on HttpRequest class for Azure Functions. Usually Azure Functions takes HttpRequest class for extracting request. However, the tutorial described HttpRequestMessage. I was really confused because HttpRequestMessage works partly, but it does not support Body property.