ENGCOM-1773: [Forwardport] Wrong invoice prefix in multistore setup due to default store #15665

 - Merge Pull Request #15665 from vgelani/magento2:2.3-develop-PR-port-15332
 - Merged commits:
   1. d5c3952

Author: magento-engcom-team

app/code/Magento/Sales/Model/ResourceModel/EntityAbstract.php

@@ -123,10 +123,15 @@ protected function _beforeSave(\Magento\Framework\Model\AbstractModel $object)
     {
         /** @var \Magento\Sales\Model\AbstractModel $object */
         if ($object instanceof EntityInterface && $object->getIncrementId() == null) {
+            $store = $object->getStore();
+            $storeId = $store->getId();
+            if ($storeId === null) {
+                $storeId = $store->getGroup()->getDefaultStoreId();
+            }
             $object->setIncrementId(
                 $this->sequenceManager->getSequence(
                     $object->getEntityType(),
-                    $object->getStore()->getGroup()->getDefaultStoreId()
+                    $storeId
                 )->getNextValue()
             );
         }