public function getDirectories($directory = '', $recursive = false, $filterPatterns = [])
{
list($prefix, $directory) = $this->filterPrefix($directory);
if (($fs = $this->getFilesystem($prefix)) === null) {
throw new ReadException("No filesystem saved under prefix [{$prefix}].");
}
return $fs->getDirectories($directory, $recursive, $filterPatterns);
}