code: public function onPreDelete(ResourceEventInterface $event)
      {
          $this->throwIllegalOperationIfAdjustmentIsImmutable($event);
  
          $adjustment = $this->getAdjustmentFromEvent($event);
  
          // Pre load adjustments collection
          if (null === $adjustable = $adjustment->getAdjustable()) {
              return;
          }
  
          $adjustable->getAdjustments()->toArray();
      }
docs: Pre delete event handler.
  
  @param ResourceEventInterface $event
  
  @throws IllegalOperationException