code: protected function assertAdjustmentType(Model\AdjustmentInterface $adjustment, string $expected): void
      {
          if ($expected !== $type = $adjustment->getType()) {
              throw new Exception\InvalidArgumentException("Unexpected adjustment type '$type'.");
          }
      }
docs: Asserts that the adjustment type is as expected.
  
  @param Model\AdjustmentInterface $adjustment
  @param string                    $expected