protected function _deserializeOptionalExtractionPaths(DOMXPath $xpath)
	{
		foreach ($this->_optionalExtractionPaths as $setter => $path) {
			$foundNode = $xpath->query($path)->item(0);
			if ($foundNode) {
				$this->$setter($foundNode->nodeValue);
			}
		}
		return $this;
	}