pocketmine\entity\WitherSkeleton::getDrops PHP Method

    public function getDrops()
    {
        $drops = [];
        if ($this->lastDamageCause instanceof EntityDamageByEntityEvent and $this->lastDamageCause->getEntity() instanceof Player) {
            $drops = [ItemItem::get(ItemItem::COAL, 0, mt_rand(0, 1)), ItemItem::get(ItemItem::BONE, 0, mt_rand(0, 2))];
        }
        if ($this->lastDamageCause instanceof EntityDamageByEntityEvent and $this->lastDamageCause->getEntity() instanceof Creeper && $this->lastDamageCause->getEntity()->isPowered()) {
            $drops = [ItemItem::get(ItemItem::SKULL, 1, 1)];
        }
        return $drops;
    }