public function __construct()
{
$this->distributors = new ArrayCollection();
$this->manufacturers = new ArrayCollection();
$this->parameters = new ArrayCollection();
$this->attachments = new ArrayCollection();
$this->stockLevels = new ArrayCollection();
$this->projectParts = new ArrayCollection();
$this->setCreateDate(new \DateTime());
$this->setNeedsReview(false);
}