[UC-3] Move const to interface

Author: DominikWolos

src/Api/ProductApi.php

@@ -16,8 +16,6 @@
 
 final class ProductApi extends AbstractClient implements ProductApiInterface
 {
-    public const GET_PRODUCT_BY_CUSTOM_ID_ENDPOINT = '/products-by-id/%s/product_event/';
-
     public function getProductByCustomId(UserComApiAwareInterface $resource, int $productId): ?array
     {
         $url = $this->getApiEndpointUrl($resource, sprintf(self::GET_PRODUCT_BY_CUSTOM_ID_ENDPOINT, $productId));

src/Api/ProductApiInterface.php

@@ -15,5 +15,7 @@
 
 interface ProductApiInterface
 {
+    public const GET_PRODUCT_BY_CUSTOM_ID_ENDPOINT = '/products-by-id/%s/product_event/';
+
     public function getProductByCustomId(UserComApiAwareInterface $resource, int $productId): ?array;
 }