New API's (#94)

* Added Handler

* created slowResponse, 500Response, 408Response API.

* Updated as per the review points.

* Updated endpoints and related code

* changed endpoint names.

* Added comments for APIs.

* Update src/checkoutservice/main.go

commit for change suggested

Co-authored-by: Dmitrii Anoshin <anoshindx@gmail.com>

* Updated GenerateSalesTax as per review point.

* Updated code for timeout handling

Co-authored-by: sonu0610 <sonu.jain@crestsysdata.com>
Co-authored-by: Dmitrii Anoshin <anoshindx@gmail.com>

pb/demo.proto

@@ -207,6 +207,22 @@ message SendOrderConfirmationRequest {
 
 service CheckoutService {
     rpc PlaceOrder(PlaceOrderRequest) returns (PlaceOrderResponse) {}
+    rpc GeneratePayment(GeneratePaymentRequest) returns (Empty) {}
+    rpc GenerateSalesTax(GenerateSalesTaxRequest) returns (Empty) {}
+    rpc GenerateCartEmpty(GenerateCartEmptyRequest) returns (Empty) {}
+}
+
+message GeneratePaymentRequest {
+    string product_id = 1;
+    int32  quantity = 2;
+}
+
+message GenerateSalesTaxRequest {
+    string country = 1;
+}
+
+message GenerateCartEmptyRequest {
+    uint32 delay = 1;
 }
 
 message PlaceOrderRequest {