inventory: populate missing return type information

src/pocketmine/inventory/BaseInventory.php

@@ -84,6 +84,8 @@ abstract class BaseInventory implements Inventory{
 	 * WARNING: If the size is smaller, any items past the new size will be lost.
 	 *
 	 * @param int $size
+	 *
+	 * @return void
 	 */
 	public function setSize(int $size){
 		$this->slots->setSize($size);

src/pocketmine/inventory/DoubleChestInventory.php

@@ -142,6 +142,9 @@ class DoubleChestInventory extends ChestInventory implements InventoryHolder{
 		return $this->right;
 	}
 
+	/**
+	 * @return void
+	 */
 	public function invalidate(){
 		$this->left = null;
 		$this->right = null;

src/pocketmine/inventory/EnderChestInventory.php

@@ -53,6 +53,8 @@ class EnderChestInventory extends ChestInventory{
 	 * Set the holder's position to that of a tile
 	 *
 	 * @param EnderChest $enderChest
+	 *
+	 * @return void
 	 */
 	public function setHolderPosition(EnderChest $enderChest){
 		$this->holder->setComponents($enderChest->getFloorX(), $enderChest->getFloorY(), $enderChest->getFloorZ());

src/pocketmine/inventory/FurnaceRecipe.php

@@ -44,6 +44,8 @@ class FurnaceRecipe implements Recipe{
 
 	/**
 	 * @param Item $item
+	 *
+	 * @return void
 	 */
 	public function setInput(Item $item){
 		$this->ingredient = clone $item;

src/pocketmine/inventory/PlayerInventory.php

@@ -97,7 +97,7 @@ class PlayerInventory extends BaseInventory{
 	 *
 	 * @throws \InvalidArgumentException
 	 */
-	private function throwIfNotHotbarSlot(int $slot){
+	private function throwIfNotHotbarSlot(int $slot) : void{
 		if(!$this->isHotbarSlot($slot)){
 			throw new \InvalidArgumentException("$slot is not a valid hotbar slot index (expected 0 - " . ($this->getHotbarSize() - 1) . ")");
 		}
@@ -132,6 +132,7 @@ class PlayerInventory extends BaseInventory{
 	 * @param bool $send Whether to send updates back to the inventory holder. This should usually be true for plugin calls.
 	 *                    It should only be false to prevent feedback loops of equipment packets between client and server.
 	 *
+	 * @return void
 	 * @throws \InvalidArgumentException if the hotbar slot is out of range
 	 */
 	public function setHeldItemIndex(int $hotbarSlot, bool $send = true){
@@ -170,6 +171,8 @@ class PlayerInventory extends BaseInventory{
 	 * Sends the currently-held item to specified targets.
 	 *
 	 * @param Player|Player[] $target
+	 *
+	 * @return void
 	 */
 	public function sendHeldItem($target){
 		$item = $this->getItemInHand();
@@ -201,6 +204,9 @@ class PlayerInventory extends BaseInventory{
 		return 9;
 	}
 
+	/**
+	 * @return void
+	 */
 	public function sendCreativeContents(){
 		//TODO: this mess shouldn't be in here
 		$holder = $this->getHolder();