private async Task <TResult> PostXmlAsync <T, TResult>(string path, T instance)
where T : notnull
where TResult : notnull
{
string url = baseUrl + Version + path;
var content = new ByteArrayContent(Route53Serializer <T> .SerializeToUtf8Bytes(instance));
content.Headers.ContentType = new MediaTypeHeaderValue("application/xml");
string responseText = await SendAsync(new HttpRequestMessage(HttpMethod.Post, url) {
Content = content
});
return(Route53Serializer <TResult> .DeserializeXml(responseText));
}