protected function loadMappingFile($file)
    {
        $xmlElement = simplexml_load_file($file);
        $types = array('mapped-superclass', 'entity', 'document');

        foreach ($types as $type) {
            if (isset($xmlElement->$type)) {
                $className = $this->getAttribute($xmlElement->$type, 'name');

                return array($className => $xmlElement->$type);
            }
        }

        return null;
    }
protected function loadMappingFile($file)
    {
        $xmlElement = simplexml_load_file($file);
        $types = array('mapped-superclass', 'entity', 'document');

        foreach ($types as $type) {
            if (isset($xmlElement->$type)) {
                $className = $this->getAttribute($xmlElement->$type, 'name');

                return array($className => $xmlElement->$type);
            }
        }

        return null;
    }
{@inheritDoc}