pocketmine\event\Event::setCancelled PHP Method

    public function setCancelled($value = true)
    {
        if (!$this instanceof Cancellable) {
            throw new \BadMethodCallException("Event is not Cancellable");
        }
        /** @var Event $this */
        $this->isCancelled = (bool) $value;
    }

 public function permissionCheck(Event $event)
 {
     /** @var $player Player */
     $player = $event->getPlayer();
     if ($event instanceof PlayerInteractEvent) {
         $block = $event->getBlock()->getSide($event->getFace());
     } else {
         $block = $event->getBlock();
     }
     $x = $block->getX();
     $z = $block->getZ();
     $level = $block->getLevel()->getFolderName();
     if (in_array($level, $this->config->get("non-check-worlds"))) {
         return false;
     }
     //$exist = false;
     //$result = $this->land->query("SELECT owner,invitee FROM land WHERE level = '$level' AND endX > $x AND endZ > $z AND startX < $x AND startZ < $z");
     //if(!is_array($info)) goto checkLand;
     $info = $this->db->canTouch($x, $z, $level, $player);
     if ($info === -1) {
         if ($this->config->get("white-world-protection")) {
             if (in_array($level, $this->config->get("white-world-protection")) and !$player->hasPermission("economyland.land.modify.whiteland")) {
                 $player->sendMessage($this->getMessage("not-owned"));
                 $event->setCancelled();
                 if ($event->getItem()->isPlaceable()) {
                     $this->placeQueue[$player->getName()] = true;
                 }
                 return false;
             }
         }
     } elseif ($info !== true) {
         $player->sendMessage($this->getMessage("no-permission", array($info["owner"], "", "")));
         $event->setCancelled();
         if ($event instanceof PlayerInteractEvent) {
             if ($event->getItem()->isPlaceable()) {
                 $this->placeQueue[$player->getName()] = true;
             }
         }
         return false;
     }
     return true;
 }