protected function setMetaDataProperties(array $config)
    {
        if (empty($this->metaDataProperties)) {
            $itemTypes = $this->item->getTypes();
            $classType = reset($itemTypes);

            if (!$classType->isClass()) {
                throw new ExtractorException('Item class type do not exists');
            }

            $this->metaDataProperties = $this->getAvailableMetaDataProperties($classType, $config['excludedProperties']);
        }
    }