manufacturer-information/Modules/Application/Model/ManufacturerInfoList.php

<?php
    
declare(strict_types=1);

namespace D3\ManufacturerInformation\Modules\Application\Model;


use D3\ManufacturerInformation\Application\Model\Constants;
use OxidEsales\Eshop\Application\Model\Manufacturer;
use OxidEsales\Eshop\Application\Model\ManufacturerList;
use OxidEsales\Eshop\Core\Field;

class ManufacturerInfoList extends ManufacturerInfoList_parent
{
    /**
     * @param Manufacturer|D3ManufacturerLongDesc $oManufacturer
     * @return void
     */
    protected function _addCategoryFields($oManufacturer)
    {
        parent::_addCategoryFields($oManufacturer);
        
        $oManufacturer->oxcategories__oxlongdesc = new Field($oManufacturer->getFieldData(Constants::D3_OXMANUFACTURERS_LONGDESC_FIELDNAME), Field::T_RAW);
    }
}