code: protected function getSaleFromAdjustment(Model\SaleAdjustmentInterface $adjustment)
      {
          if (null !== $sale = $adjustment->getSale()) {
              return $sale;
          }
  
          $cs = $this->persistenceHelper->getChangeSet($adjustment, $this->getSalePropertyPath());
  
          if (!empty($cs)) {
              return $cs[0];
          }
  
          return null;
      }
docs: Returns the sale from the given sale adjustment (looking into change set).
  
  @param Model\SaleAdjustmentInterface $adjustment
  
  @return Model\SaleInterface|null