protected function feedRequiredFiles(Item $item)
    {
        $this->requiredFiles = [];
        $this->portableObjects = [];
        $this->picModels = [];

        $models = $this->getPortableFactory()->getModels();

        foreach ($models as $model) {
            $className = $model->getQtiElementClassName();
            $portableElementsXml = $item->getComposingElements($className);
            foreach($portableElementsXml as $portableElementXml) {
                $this->parsePortableElement($model, $portableElementXml);
            }
        }
    }