private function findExtensionsDirectories(Container $app)
    {
        $directories = $app['config.finder']
            ->ignoreUnreadableDirs()
            ->directories()
            ->name('*Extension')
            ->in($app['app.extensions.dir'])
            ->depth('< 3')
            ->sortByName()
        ;

        return $directories;
    }
private function findExtensionsDirectories(Container $app)
    {
        $directories = $app['config.finder']
            ->ignoreUnreadableDirs()
            ->directories()
            ->name('*Extension')
            ->in($app['app.extensions.dir'])
            ->depth('< 3')
            ->sortByName()
        ;

        return $directories;
    }
Returns all valid extensions folders

@param Container $app

@return Finder