public override string ToQueryString()
{
var builder = new RequestBuilder();
builder.AddTopLevelElement("merchant_id", MerchantId);
builder.AddTopLevelElement("redirect_uri", RedirectUri);
builder.AddTopLevelElement("scope", Scope);
builder.AddTopLevelElement("state", State);
builder.AddTopLevelElement("client_id", ClientId);
foreach (var paymentMethod in PaymentMethods) {
builder.AddTopLevelElement("payment_methods[]", paymentMethod);
}
builder.AddElement("user", User);
builder.AddElement("business", Business);
return builder.ToQueryString();
}