public function getProductCategoryIds()
    {

        // initialize the array with the product's category IDs
        $categoryIds = array();

        // query whether or not category IDs are available for the actual product entity
        if (isset($this->productCategoryIds[$lastEntityId = $this->getLastEntityId()])) {
            $categoryIds = $this->productCategoryIds[$lastEntityId];
        }

        // return the array with the product's category IDs
        return $categoryIds;
    }