pocketmine\block\WaterLily::place PHP Method

    public function place(Item $item, Block $block, Block $target, $face, $fx, $fy, $fz, Player $player = null)
    {
        if ($target instanceof Water) {
            $up = $target->getSide(Vector3::SIDE_UP);
            if ($up->getId() === Block::AIR) {
                $this->getLevel()->setBlock($up, $this, true, true);
                return true;
            }
        }
        return false;
    }