private static void verifyPayment(Payment payment)
        {
            string     resultString = "".ToString();
            JSONObject jsonObject   = new JSONObject();

            jsonObject.Put("payload", payment.Payload);

            string verifystring = (string)jsonObject;
            //Map<string, string> headers = new HashMap<>();
            //headers.Put("Content-Type", "application/json; charset=UTF-8");
            //headers.Put(merchantApiHeaderKeyForApiSecretKey, merchantApiSecretKey);
            Dictionary <string, string> headers = new Dictionary <string, string>();

            headers.Add("Content-Type", "application/json; charset=UTF-8");
            headers.Add(merchantApiHeaderKeyForApiSecretKey, merchantApiSecretKey);
            //
            AsyncHttpClient.Post(merchantServerUrl + VERIFY, headers, verifystring, new HttpResponseCallback
            {
                Success = (response) =>
                {
                    Java.Lang.String mString      = new Java.Lang.String(response, Charset.ForName("UTF-8"));
                    JSONObject jsonVerifyResponse = new JSONObject((string)mString);
                    Java.Lang.String authResponse = new Java.Lang.String(jsonVerifyResponse.GetString("authResponse"));
                    if (authResponse.EqualsIgnoreCase(payment.GetPaymentStatus().ToString()))
                    {
                        resultString = "Payment is " + payment.GetPaymentStatus().ToString().ToLower() + " and verified.";
                    }
                    else
                    {
                        resultString = "Failed to verify payment.";
                    }
                },
                Failure = (th) =>
                {
                    Toast.MakeText(context, resultString, ToastLength.Long).Show();
                }
            });
        }