VaryByParam wildcard not working

Hey Kristensen,

I greatly support the amazing things you create actually. Today I needed outputcache middleware for .net core and I was in the intent of creating one by myself. Then I found your solution which is working great. Thanks for it actually.

However, I found that you have not checked wildcard as it was working in previous implementations of the .net framework; varying by all query/header headers is not possible for the moment in your solution.