code: protected function getHash()
  	{
  		@trigger_error('Using Folder::getHash() has been deprecated and will no longer work in Contao 5.0. Use Dbafs::getFolderHash() instead.', E_USER_DEPRECATED);
  
  		$arrFiles = array();
  
  		/** @var \SplFileInfo[] $it */
  		$it = new \RecursiveIteratorIterator(
  			new \RecursiveDirectoryIterator(
  				$this->strRootDir . '/' . $this->strFolder,
  				\FilesystemIterator::UNIX_PATHS|\FilesystemIterator::FOLLOW_SYMLINKS|\FilesystemIterator::SKIP_DOTS
  			), \RecursiveIteratorIterator::SELF_FIRST
  		);
  
  		foreach ($it as $i)
  		{
  			if (strncmp($i->getFilename(), '.', 1) !== 0)
  			{
  				$arrFiles[] = substr($i->getPathname(), \strlen($this->strRootDir . '/' . $this->strFolder . '/'));
  			}
  		}
  
  		return md5(implode('-', $arrFiles));
  	}
docs: Return the MD5 hash of the folder
  
  @return string The MD5 has
  
  @deprecated Use Dbafs::getFolderHash() instead