private static void CopyHeaders(HttpContentHeaders input, Windows.Web.Http.Headers.HttpContentHeaderCollection output)
 {
     foreach (var header in input)
     {
         output.Add(header.Key, GetHeaderValue(header.Key, header.Value));
     }
 }
 private static void CopyHeaders(Windows.Web.Http.Headers.HttpContentHeaderCollection input, HttpContentHeaders output)
 {
     foreach (var header in input)
     {
         if (!string.Equals(header.Key, "Expires", StringComparison.OrdinalIgnoreCase) || header.Value != "-1")
         {
             output.Add(header.Key, header.Value);
         }
     }
 }