private string GetAuthorizationHeader(OAuthRequest oAuthRequest)
{
var request = new Common.Http.HttpRequest(Settings.SigningUrl)
{
Method = HttpMethod.Post,
};
request.Headers.Set("Content-Type", "application/json");
var payload = oAuthRequest.ToJson();
_logger.Trace(payload);
request.SetContent(payload);
var response = _httpClient.Post <AuthorizationHeader>(request).Resource;
return(response.Authorization);
}