How to get Environment from Global.asax to derive SignInMessage Object

问题

I'm trying to get Client Id from Global.asax begin_request to identify the client logging in.

I understand that this can be gotten from SignInMessage using OWIN extensions. OwinEnvironmentExtensions class require Owin Environment (IDictionary).

My question is, how do I get Owin Environment from global.asax?

来源：https://stackoverflow.com/questions/54078157/how-to-get-environment-from-global-asax-to-derive-signinmessage-object