private function parseFileToDOM($file)
{
try {
$dom = XmlUtils::loadFile($file, array($this, 'validateSchema'));
} catch (\InvalidArgumentException $e) {
throw new InvalidArgumentException(sprintf('Unable to parse file "%s".', $file), $e->getCode(), $e);
}
$this->validateExtensions($dom, $file);
return $dom;
}