MAGETWO-44109: Import Custom Options grid contains Downloadable product if...

MAGETWO-44109: Import Custom Options grid contains Downloadable product if Import Custom Options for Simple product

app/code/Magento/Catalog/Block/Adminhtml/Product/Edit/Tab/Options/Option.php

@@ -462,6 +462,11 @@ class Option extends Widget
         return $this->getUrl('catalog/*/customOptions');
     }
 
+    /**
+     * Return current product id
+     *
+     * @return null|int
+     */
     public function getCurrentProductId()
     {
         return $this->getProduct()->getId();