Drupal Commerce 2 on paid event

<?php

declare(strict_types=1);

namespace Drupal\MYMODULE\EventSubscriber;

use Drupal\commerce_order\Event\OrderEvent;
use Drupal\commerce_order\Event\OrderEvents;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;

/**
 * Order Paid Subscriber.
 */
final class OrderPaidSubscriber implements EventSubscriberInterface {

 /**
  * {@inheritdoc}
  */
 public static function getSubscribedEvents(): array {
   return [
     OrderEvents::ORDER_PAID => ['onPaid', -100],
   ];
 }
 
 /**
  * Apply transition to validate order.
  *
  * @param \Drupal\commerce_order\Event\OrderEvent $event
  *   The event.
  */
 public function onPaid(OrderEvent $event) {
   // Some code.
 }
 
}