protected function toArray()
    {
        $arr = [];
        $arr[Resources::XTAG_NAMESPACE] = [
            Resources::WA_XML_NAMESPACE => null,
        ];

        Utilities::addIfNotEmpty(Resources::XTAG_LABEL, $this->_label, $arr);
        Utilities::addIfNotEmpty(
            Resources::XTAG_DESCRIPTION,
            $this->_description,
            $arr
        );
        Utilities::addIfNotEmpty(
            Resources::XTAG_LOCATION,
            $this->_location,
            $arr
        );

        return $arr;
    }