pocketmine\inventory\BaseInventory::sendContents PHP Method

    public function sendContents($target)
    {
        if ($target instanceof Player) {
            $target = [$target];
        }
        $pk = new ContainerSetContentPacket();
        $pk->slots = [];
        for ($i = 0; $i < $this->getSize(); ++$i) {
            $pk->slots[$i] = $this->getItem($i);
        }
        foreach ($target as $player) {
            if (($id = $player->getWindowId($this)) === -1 or $player->spawned !== true) {
                $this->close($player);
                continue;
            }
            $pk->windowid = $id;
            $player->dataPacket($pk);
        }
    }