Need to obtain header key value pairs from web API 2 using filters

Question

I desire to use a web api filter to be able to collect the following from the request and response:

The request url, The method ( i.e. Get, POST…), both the request and response header key value pairs.

I searched stackoverflow at the following link and there is a good example of using a filter to capture the content.

Need to log asp.net webapi 2 request and response body to a database

I changed the following code from the example in the link above:

var responseBody = await result.Content.ReadAsStringAsync();

To:

var responseBody = await result.Header…; // when I picked Header methods – they would not work with await

Do Have a suggestion?