code: public function protect()
  	{
  		@trigger_error('Using DC_Folder::protect() has been deprecated and will no longer work in Contao 5.0. Use Contao\Folder::protect() and Contao\Folder::unprotect() instead.', E_USER_DEPRECATED);
  
  		if (!is_dir($this->strRootDir . '/' . $this->intId))
  		{
  			throw new InternalServerErrorException('Resource "' . $this->intId . '" is not a directory.');
  		}
  
  		// Protect or unprotect the folder
  		if (file_exists($this->strRootDir . '/' . $this->intId . '/.public'))
  		{
  			$objFolder = new Folder($this->intId);
  			$objFolder->protect();
  
  			$this->import(Automator::class, 'Automator');
  			$this->Automator->generateSymlinks();
  
  			$this->log('Folder "'.$this->intId.'" has been protected', __METHOD__, TL_FILES);
  		}
  		else
  		{
  			$objFolder = new Folder($this->intId);
  			$objFolder->unprotect();
  
  			$this->import(Automator::class, 'Automator');
  			$this->Automator->generateSymlinks();
  
  			$this->log('The protection from folder "'.$this->intId.'" has been removed', __METHOD__, TL_FILES);
  		}
  
  		$this->redirect($this->getReferer());
  	}
docs: Protect a folder
  
  @throws InternalServerErrorException
  
  @deprecated Deprecated since Contao 4.7 to be removed in 5.0.
  Use Contao\Folder::protect() and Contao\Folder::unprotect() instead.