[AFP-58] Work on DELETE product controller

src/main/java/com/nisum/ascend/inventory/controller/ProductController.java

@@ -9,6 +9,7 @@ import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RestController;
 import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
 
 @RestController
 @RequestMapping("/api/products")
@@ -17,8 +18,10 @@ public class ProductController {
     ProductService productService;
 
     @DeleteMapping(value = "/{sku}")
-    public void deleteProduct(@PathVariable String sku) {
-        productService.removeProductBySku(sku).subscribe();
+    public Mono<ResponseEntity<Void>> deleteProduct(@PathVariable String sku) {
+        return productService.removeProductBySku(sku)
+                .map( res -> ResponseEntity.ok().<Void>build())
+                .defaultIfEmpty(ResponseEntity.notFound().build());
     }
 
     @GetMapping()