https://learn.microsoft.com/ja-jp/dotnet/api/system.net.webrequest.registerprefix?view=netframework-4.8.1&viewFallbackFrom=net-10.0
WebRequest.RegisterPrefix(String, IWebRequestCreate) Method (System.Net) | Microsoft Learn
Registers a WebRequest descendant for the specified URI.
net microsoftwebrequeststringmethodsystem