private string BuildPayload(WebhookKind kind, string id)
{
var currentTime = DateTime.Now.ToUniversalTime().ToString("u");
var payload = string.Format("<notification><timestamp type=\"datetime\">{0}</timestamp><kind>{1}</kind><subject>{2}</subject></notification>", currentTime, kind, SubjectSampleXml(kind, id));
return Convert.ToBase64String(Encoding.GetEncoding(0).GetBytes(payload)) + '\n';
}