code: public function onUpdate(ResourceEventInterface $event)
      {
          $adjustment = $this->getAdjustmentFromEvent($event);
  
          if ($this->persistenceHelper->isChanged($adjustment, ['amount', 'mode', 'type'])) {
              $this->scheduleSaleContentChangeEvent($adjustment);
          }
      }
docs: Update event handler.
  
  @param ResourceEventInterface $event
  
  @throws \Ekyna\Component\Resource\Exception\ResourceExceptionInterface