public AuthenticationHeaderValue CreateAuthorizationHeader()
{
if (Scheme.Equals(SupportedSchemes.Basic, StringComparison.OrdinalIgnoreCase))
return new AuthenticationHeaderValue(
Scheme, Convert.ToBase64String(Encoding.ASCII.GetBytes(Username + ":" + Password)));
if (Scheme.Equals(SupportedSchemes.Token, StringComparison.OrdinalIgnoreCase))
return new AuthenticationHeaderValue(Scheme, Token);
throw new InvalidOperationException(UnsupportedSchemeMessage(Scheme));
}