protected function setDefaultOptions(OptionsResolverInterface $resolver)
{
$resolver->setRequired(array('directory'));
$resolver->setDefaults(array('mode' => self::MODE_DIRECTORY_AS_CATEGORY, 'include' => array(), 'limit' => null));
$resolver->setAllowedValues(array('mode' => array(self::MODE_DOCUMENT_AS_CATEGORY, self::MODE_DIRECTORY_AS_CATEGORY)));
$resolver->setAllowedTypes(array('directory' => 'string', 'mode' => 'int', 'include' => 'array'));
}