Why cant I see the Content-Encoding: gzip response in my c# HttpClient response header?

I'm making a simple c# program to establish if server side compression is available/enabled on various servers. This is my request code below.

using (var client = new HttpClient())
{
    client.Timeout = new TimeSpan(0, 0, 5);
    client.DefaultRequestHeaders.Add("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8");
    client.DefaultRequestHeaders.Add("User-Agent", "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/48.0.2564.97 Safari/537.36");
    client.DefaultRequestHeaders.Add("Accept-Encoding", "gzip, deflate, sdch, br");
    var httpClientResponse = client.GetAsync(websiteURL).Result;
    string header = httpClientResponse.Headers.GetValues("Content-Encoding").First();
}

I can see by watching the request in fiddler that compression is enabled for this request however I can't seem to extract that information from the response headers in code.

These are the full headers for request and response.

GET https://www.dobbies.com/ HTTP/1.1
Accept: text/html, application/xhtml+xml, application/xml; q=0.9, image/webp, */*; q=0.8
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/48.0.2564.97 Safari/537.36
Accept-Encoding: gzip, deflate, sdch, br
Host: www.dobbies.com

HTTP/1.1 200 OK
Cache-Control: private
Content-Type: text/html; charset=utf-8
Content-Encoding: gzip
Vary: Accept-Encoding
Server: 
Set-Cookie: ASP.NET_SessionId=hx1rb34ottgfritgt3rciql4; path=/; secure; HttpOnly
X-Frame-Options: SAMEORIGIN
X-Content-Type-Options: nosniff
Strict-Transport-Security: max-age=31536000
X-Xss-Protection: 1; mode=block
Date: Fri, 07 Apr 2017 08:06:17 GMT
Content-Length: 16836

This is what I get when I use httpClientResponse.Headers

{
    Vary: Accept-Encoding
    X-Frame-Options: SAMEORIGIN
    X-Content-Type-Options: nosniff
    Strict-Transport-Security: max-age=31536000
    X-Xss-Protection: 1; mode=block
    Cache-Control: private
    Date: Fri, 07 Apr 2017 08:06:17 GMT
    Set-Cookie: ASP.NET_SessionId=hx1rb34ottgfritgt3rciql4; path=/; secure; HttpOnly
    Server: 
}

As you can see header of Content-Encoding: gzip is missing in the response.

Why would this header be missing? Along with others. Give me back my headers!

Solution

Found the problem.

The HttpResponseMessage returned by HttpClient methods has two header properties:

HttpResponseMessage.Headers is an HttpResponseHeaders with generic response headers

HttpResponseMessage.Content.Headers is an HttpContentHeaders with content-specific headers like Content-Type