internal static void AddKnownHeaders(HashSet<string> headerSet)
{
Debug.Assert(headerSet != null);
headerSet.Add(HttpKnownHeaderNames.CacheControl);
headerSet.Add(HttpKnownHeaderNames.Connection);
headerSet.Add(HttpKnownHeaderNames.Date);
headerSet.Add(HttpKnownHeaderNames.Pragma);
headerSet.Add(HttpKnownHeaderNames.Trailer);
headerSet.Add(HttpKnownHeaderNames.TransferEncoding);
headerSet.Add(HttpKnownHeaderNames.Upgrade);
headerSet.Add(HttpKnownHeaderNames.Via);
headerSet.Add(HttpKnownHeaderNames.Warning);
}