pocketmine\inventory\PlayerInventory::onSlotChange PHP Метод

    public function onSlotChange($index, $before, $send)
    {
        if ($send) {
            $holder = $this->getHolder();
            if (!$holder instanceof Player or !$holder->spawned) {
                return;
            }
            parent::onSlotChange($index, $before, $send);
        }
        if ($index === $this->itemInHandIndex) {
            $this->sendHeldItem($this->getHolder()->getViewers());
            if ($send) {
                $this->sendHeldItem($this->getHolder());
            }
        } elseif ($index >= $this->getSize()) {
            //Armour equipment
            $this->sendArmorSlot($index, $this->getViewers());
            $this->sendArmorSlot($index, $this->getHolder()->getViewers());
        }
    }