code: protected function getItemFromAdjustment(Model\SaleItemAdjustmentInterface $adjustment)
      {
          if (null !== $item = $adjustment->getItem()) {
              return $item;
          }
  
          $cs = $this->persistenceHelper->getChangeSet($adjustment, 'item');
  
          if (!empty($cs)) {
              return $cs[0];
          }
  
          return null;
      }
docs: Returns the sale item from the given sale item adjustment (looking into change set).
  
  @param Model\SaleItemAdjustmentInterface $adjustment
  
  @return Model\SaleItemInterface|null