Issue #3198668: Order onPaid event called twice

src/EventSubscriber/InvoiceSubscriber.php

@@ -4,6 +4,7 @@ namespace Drupal\commerce_invoice\EventSubscriber;
 
 use Drupal\state_machine\Event\WorkflowTransitionEvent;
 use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+use Drupal\commerce_order\Entity\OrderInterface;
 
 class InvoiceSubscriber implements EventSubscriberInterface {
 
@@ -41,9 +42,11 @@ class InvoiceSubscriber implements EventSubscriberInterface {
   public function onPayPostTransition(WorkflowTransitionEvent $event) {
     /** @var \Drupal\commerce_invoice\Entity\InvoiceInterface $invoice */
     $invoice = $event->getEntity();
+    $orders_field = $invoice->get('orders');
     // When an invoice is paid, we need to mark the referenced orders as paid.
-    foreach ($invoice->getOrders() as $order) {
-      if ($order->isPaid()) {
+    foreach ($orders_field as $item) {
+      $order = $item->entity;
+      if (!$order instanceof OrderInterface || $order->isPaid()) {
         continue;
       }
       $order->setTotalPaid($order->getTotalPrice());