ASP.NET Core 2.0 AzureAD Authentication not working

I have an ASP.NET Core 2.0 application setup that I want to use AzureAd for the authentication with my company’s directory. I have setup the classes and startup method and have the authentication piece working, the problem that I’m having is that I’m trying to setup and event handler to the OnAuthorizationCodeReceived event, so that I can request a user token that will then be used for Microsoft graph calls.