pocketmine\block\Liquid::flowIntoBlock PHP Method

    private function flowIntoBlock(Block $block, $newFlowDecay)
    {
        if ($block->canBeFlowedInto()) {
            if ($block instanceof Lava) {
                $this->triggerLavaMixEffects($block);
            } elseif ($block->getId() > 0) {
                $this->getLevel()->useBreakOn($block);
            }
            $this->getLevel()->setBlock($block, Block::get($this->getId(), $newFlowDecay), true);
            $this->getLevel()->scheduleUpdate($block, $this->tickRate());
        }
    }