{
  "error" : "invalid_token"
}

var values = new Dictionary<string, string> { { "token", token.Token } };
var content = new FormUrlEncodedContent(values);

HttpClient client = new HttpClient();
var response =
    await client.PostAsync("https://accounts.google.com/o/oauth2/revoke",content);

var responseString = await response.Content.ReadAsStringAsync();
Log.Info(responseString);

{
  "error" : "invalid_request",
  "error_description" : "Missing required parameter: token"
}