Changed post route to return a response entity instead of a Mono

src/main/java/com/nisum/ascend/promotions/controller/PromotionsController.java

@@ -14,6 +14,7 @@ import reactor.core.publisher.Mono;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Optional;
 
 @RestController
 @RequestMapping("/api/promos")
@@ -39,8 +40,10 @@ public class PromotionsController {
     }
 
     @PostMapping("")
-    public Mono<PromotionDto> createPromotion(@RequestBody Promotion newPromotion){
-        return promotionService.createPromotion(newPromotion).onErrorMap(throwable -> new PromotionAlreadyExistsException());
+    public ResponseEntity<Mono<PromotionDto>> createPromotion(@RequestBody Promotion newPromotion){
+        Mono<PromotionDto> responseData = promotionService.createPromotion(newPromotion)
+                .onErrorResume(throwable -> Mono.error(new PromotionAlreadyExistsException()));
+        return ResponseEntity.ok(responseData);
     }
 
     @PostMapping("/bulkSearch")