code: public static function scanAndRegister()
  	{
  		$strCacheDir = System::getContainer()->getParameter('kernel.cache_dir');
  
  		// Try to load from cache
  		if (file_exists($strCacheDir . '/contao/config/autoload.php'))
  		{
  			include $strCacheDir . '/contao/config/autoload.php';
  		}
  		else
  		{
  			try
  			{
  				$files = System::getContainer()->get('contao.resource_locator')->locate('config/autoload.php', null, false);
  			}
  			catch (\InvalidArgumentException $e)
  			{
  				$files = array();
  			}
  
  			foreach ($files as $file)
  			{
  				include $file;
  			}
  		}
  
  		self::register();
  	}
docs: Scan the module directories for config/autoload.php files and then
  register the autoloader on the SPL stack