Arrow: allow controlling pickup mode (like PC)

This allows controlling how arrows are picked up:
- by anything
- by only creative players
- by nothing

This adds new API methods to Arrow:
- getPickupMode()
- setPickupMode()

This adds new public constants to Arrow:
- PICKUP_NONE
- PICKUP_ANY
- PICKUP_CREATIVE

src/pocketmine/entity/projectile/Arrow.php

@@ -40,6 +40,12 @@ use pocketmine\Player;
 class Arrow extends Projectile{
 	public const NETWORK_ID = self::ARROW;
 
+	public const PICKUP_NONE = 0;
+	public const PICKUP_ANY = 1;
+	public const PICKUP_CREATIVE = 2;
+
+	private const TAG_PICKUP = "pickup"; //TAG_Byte
+
 	public $width = 0.25;
 	public $height = 0.25;
 
@@ -48,11 +54,26 @@ class Arrow extends Projectile{
 
 	protected $damage = 2;
 
+	/** @var int */
+	protected $pickupMode = self::PICKUP_ANY;
+
 	public function __construct(Level $level, CompoundTag $nbt, ?Entity $shootingEntity = null, bool $critical = false){
 		parent::__construct($level, $nbt, $shootingEntity);
 		$this->setCritical($critical);
 	}
 
+	protected function initEntity() : void{
+		parent::initEntity();
+
+		$this->pickupMode = $this->namedtag->getByte(self::TAG_PICKUP, self::PICKUP_ANY, true);
+	}
+
+	public function saveNBT() : void{
+		parent::saveNBT();
+
+		$this->namedtag->setByte(self::TAG_PICKUP, $this->pickupMode, true);
+	}
+
 	public function isCritical() : bool{
 		return $this->getGenericFlag(self::DATA_FLAG_CRITICAL);
 	}
@@ -95,6 +116,20 @@ class Arrow extends Projectile{
 		$this->broadcastEntityEvent(EntityEventPacket::ARROW_SHAKE, 7); //7 ticks
 	}
 
+	/**
+	 * @return int
+	 */
+	public function getPickupMode() : int{
+		return $this->pickupMode;
+	}
+
+	/**
+	 * @param int $pickupMode
+	 */
+	public function setPickupMode(int $pickupMode) : void{
+		$this->pickupMode = $pickupMode;
+	}
+
 	public function onCollideWithPlayer(Player $player) : void{
 		if($this->blockHit === null){
 			return;
@@ -107,7 +142,12 @@ class Arrow extends Projectile{
 			return;
 		}
 
-		$this->server->getPluginManager()->callEvent($ev = new InventoryPickupArrowEvent($playerInventory, $this));
+		$ev = new InventoryPickupArrowEvent($playerInventory, $this);
+		if($this->pickupMode === self::PICKUP_NONE or ($this->pickupMode === self::PICKUP_CREATIVE and !$player->isCreative())){
+			$ev->setCancelled();
+		}
+
+		$this->server->getPluginManager()->callEvent($ev);
 		if($ev->isCancelled()){
 			return;
 		}