public ATrustSigner(ATrustCredentials credentials, ATrustEnvironment environment = ATrustEnvironment.Production)
        {
            Credentials = credentials;
            var environmentDomain = environment == ATrustEnvironment.Production ? "www" : "hs-abnahme";
            var endpointUrl       = new EndpointUrl($"https://{environmentDomain}.a-trust.at/asignrkonline/v2/{Credentials.User.Value}");

            HttpClient = new SimpleHttpClient(endpointUrl);
        }
 public SimpleHttpClient(EndpointUrl endpointUrl)
 {
     EndpointUrl = endpointUrl;
 }