Download link does not get rendered in invoice email

Author: Jakob Meissner

app/code/Magento/Downloadable/Block/Sales/Order/Email/Items/Downloadable.php

@@ -68,12 +68,12 @@ public function __construct(
     public function getLinks()
     {
         $this->_purchased = $this->_purchasedFactory->create()->load(
-            $this->getItem()->getId(),
+            $this->getItem()->getOrderItemId(),
             'order_item_id'
         );
         $purchasedLinks = $this->_itemsFactory->create()->addFieldToFilter(
             'order_item_id',
-            $this->getItem()->getId()
+            $this->getItem()->getOrderItemId()
         );
         $this->_purchased->setPurchasedItems($purchasedLinks);