pocketmine\entity\Item::saveNBT PHP Method

    public function saveNBT()
    {
        parent::saveNBT();
        $this->namedtag->Item = NBT::putItemHelper($this->item);
        $this->namedtag->Health = new ShortTag("Health", $this->getHealth());
        $this->namedtag->Age = new ShortTag("Age", $this->age);
        $this->namedtag->PickupDelay = new ShortTag("PickupDelay", $this->pickupDelay);
        if ($this->owner !== null) {
            $this->namedtag->Owner = new StringTag("Owner", $this->owner);
        }
        if ($this->thrower !== null) {
            $this->namedtag->Thrower = new StringTag("Thrower", $this->thrower);
        }
    }