static bool TryRetrieveToken(HttpRequestMessage request, out string token)
{
token = string.Empty;
IEnumerable<string> authzHeaders;
if ((!request.Headers.TryGetValues("Authorization", out authzHeaders) || authzHeaders.Count() > 1)) { return false; }
var bearerToken = authzHeaders.ElementAt(0);
token = bearerToken.StartsWith("Bearer ") ? bearerToken.Substring(7) : bearerToken;
return true;
}