c# - Set Content-MD5 in get request -

i have following code:

httprequestmessage message = new httprequestmessage(httpmethod.get, uri); byte[] md5 = {my hash}; message.content.headers.contentmd5 = md5; 

the problem is, message.content null.

the client use of type system.net.http.httpclient

now question, how can send httpcontent in get request?

my solution is, created own header. planned use content-md5 caching, created own caching header.