code: protected function setItem(ItemPipelineEvent $event)
      {
          /** @var AbstractImportItem $tempItem */
          $tempItem = $event->getItem();
  
          if (!$tempItem instanceof $this->importItemClass) {
              $this->log("Item provided is not an {$this->importItemClass}", LogLevel::ERROR);
  
              return false;
          }
  
          $this->importItem = $tempItem;
  
          return true;
      }
docs: Validates the class name of event item and prepares internal document for persistence operation.
  
  @param ItemPipelineEvent $event
  
  @return bool