RazorPay Android checkout

PlatformServices.cs

using Com.Razorpay;
using System.Net.Http;
using Newtonsoft.Json 
using Xamarin.Forms; 

[assembly: Dependency(typeof(PaymentInterface))]
namespace PlatformServices
{
    public class PaymentInterface :IPaymentInterface
    {
        public void OnPaymentError(int p0, string p1, PaymentData p2)
        {
            var orderId = p2.OrderId;
            var paymentId = p2.PaymentId;
            var PaymentFailureError = p1;
        }

        public void OnPaymentSuccess(string p0, PaymentData p1)
        {
            var orderId = p1.OrderId;
            var paymentId = p1.PaymentId;
        }

        public async Task PayViaRazor()
        { 
          RazorPayload payload = new RazorPayload(); //update model class
          payload.amount = (int)amount * 100;
          payload.currency = "INR";
          payload.receipt = Helper.GenerateRefNo(); //refer the above method
          payload.payment_capture = 1;
                
            using (var httpClient = new HttpClient())
            {
                using (var request = new HttpRequestMessage(new HttpMethod("POST"), "https://api.razorpay.com/v1/orders"))
                {
                    var plainTextBytes = Encoding.UTF8.GetBytes($"{RazorPay_Key}:{RazorPay_Secret}"); //update razorpay credentials here
                    var basicAuthKey = Convert.ToBase64String(plainTextBytes);
                    request.Headers.TryAddWithoutValidation("Authorization", $"Basic {basicAuthKey}");

                    string jsonData = JsonConvert.SerializeObject(payload);
                    request.Content = new StringContent(jsonData);
                    request.Content.Headers.ContentType = MediaTypeHeaderValue.Parse("application/json");

                    var response = await httpClient.SendAsync(request);
                    string jsonResp = await response.Content.ReadAsStringAsync();
                    RazorResp resp = JsonConvert.DeserializeObject<RazorResp>(jsonResp);

                    if (!string.IsNullOrEmpty(resp.id))
                    {
                      // checkout
                      Checkout checkout = new Checkout();
                      checkout.SetImage(Resource.Drawable.splash_logo);
                      //checkout.SetFullScreenDisable(false); 
                      checkout.SetKeyID(username);
                   
                      JSONObject options = new JSONObject();
                      options.Put("name", "CodeLog");
                      options.Put("description", $"Reference No. {payload.receipt}");
                      options.Put("image", "https://s3.amazonaws.com/rzp-mobile/images/rzp.png");
                      options.Put("order_id", resp.id);//from response of step 3.
                      options.Put("theme.color", "#3399cc");
                      options.Put("currency", "INR");
                      options.Put("amount", payload.amount);//pass amount in currency subunits
                      options.Put("prefill.email", myemail);
                      options.Put("prefill.contact", mycontact);
                      checkout.Open(this, options);
                }
            }
        }
    }
}