code: public function generate()
  	{
  		$this->multiSRC = StringUtil::deserialize($this->multiSRC);
  
  		if (empty($this->multiSRC) || !\is_array($this->multiSRC))
  		{
  			return '';
  		}
  
  		$this->objFiles = FilesModel::findMultipleByUuids($this->multiSRC);
  
  		if ($this->objFiles === null)
  		{
  			return '';
  		}
  
  		return parent::generate();
  	}
docs: Check the source folder
  
  @return string