public function __construct()
{
$this->articles = new ArrayCollection();
$this->issues = new ArrayCollection();
$this->boards = new ArrayCollection();
$this->languages = new ArrayCollection();
$this->sections = new ArrayCollection();
$this->periods = new ArrayCollection();
$this->subjects = new ArrayCollection();
$this->translations = new ArrayCollection();
$this->journalApplicationUploadFiles = new ArrayCollection();
$this->journalContacts = new ArrayCollection();
$this->catalogs = new ArrayCollection();
$this->articleTypes = new ArrayCollection();
}