Apply Dylan's suggestions

src/inventory/CreativeInventory.php

@@ -27,6 +27,7 @@
 use pocketmine\inventory\data\CreativeGroup;
 use pocketmine\inventory\json\CreativeGroupData;
 use pocketmine\item\Item;
+use pocketmine\lang\Translatable;
 use pocketmine\utils\DestructorCallbackTrait;
 use pocketmine\utils\ObjectSet;
 use pocketmine\utils\SingletonTrait;
@@ -54,11 +55,10 @@ final class CreativeInventory{
 	/** @phpstan-var ObjectSet<\Closure() : void> */
 	private ObjectSet $contentChangedCallbacks;
 
-	private CreativeGroup $defaultGroup;
+	private ?CreativeGroup $defaultGroup = null;
 
 	private function __construct(){
 		$this->contentChangedCallbacks = new ObjectSet();
-		$this->defaultGroup = CreativeGroup::anonymous(CreativeCategory::ITEMS);
 
 		foreach([
 			"construction" => CreativeCategory::CONSTRUCTION,
@@ -72,9 +72,9 @@ private function __construct(){
 			);
 
 			foreach($groups as $groupData){
-				$group = new CreativeGroup(
+				$group = CreativeGroup::named(
 					$categoryId,
-					$groupData->group_name,
+					new Translatable($groupData->group_name),
 					$groupData->group_icon === null ? null : CraftingManagerFromDataHelper::deserializeItemStack($groupData->group_icon)
 				);
 				$items = array_filter(array_map(static fn($itemStack) => CraftingManagerFromDataHelper::deserializeItemStack($itemStack), $groupData->items));
@@ -105,18 +105,23 @@ public function getAll() : array{
 	}
 
 	/**
+	 * Returns the group of every item indexed by the item index.
+	 *
 	 * @return CreativeGroup[]
 	 * @phpstan-return array<int, CreativeGroup>
 	 */
-	public function getItemGroup() : array{
+	public function getItemGroups() : array{
 		return $this->groups;
 	}
 
 	public function getItem(int $index) : ?Item{
 		return isset($this->items[$index]) ? clone $this->items[$index] : null;
 	}
 
-	public function getGroup(int $index) : ?CreativeGroup{
+	/**
+	 * @see CreativeInventory::getItemIndex()
+	 */
+	public function getItemGroupByIndex(int $index) : ?CreativeGroup{
 		return $this->groups[$index] ?? null;
 	}
 
@@ -136,12 +141,16 @@ public function getItemIndex(Item $item) : int{
 	 */
 	public function add(Item $item, ?CreativeGroup $group = null) : void{
 		$this->items[] = $item;
-		$this->groups[] = $group ?? $this->defaultGroup;
-		$this->onContentChange();
 
-		if($group !== null){ // We need to create a new default group if another group is used.
-			$this->defaultGroup = CreativeGroup::anonymous(CreativeCategory::ITEMS);
+		if($group === null){
+			$this->defaultGroup ??= CreativeGroup::anonymous(CreativeCategory::ITEMS);
+			$this->groups[] = $this->defaultGroup;
+		}else{
+			$this->defaultGroup = null;
+			$this->groups[] = $group;
 		}
+
+		$this->onContentChange();
 	}
 
 	/**

src/inventory/data/CreativeGroup.php

@@ -25,43 +25,34 @@
 
 use pocketmine\inventory\CreativeCategory;
 use pocketmine\item\Item;
+use pocketmine\lang\Translatable;
 
 final class CreativeGroup{
-	private CreativeCategory $categoryId;
-	private string $name;
-	private ?Item $icon;
+	public readonly CreativeCategory $categoryId;
+	public readonly Translatable|string $name;
+	public readonly ?Item $icon;
 
-	public function __construct(CreativeCategory $categoryId, string $name, ?Item $icon = null){
-		$this->categoryId = $categoryId;
-		$this->name = $name;
-		$this->icon = $icon;
+	private function __construct(){
+		//NOOP
 	}
 
 	public static function anonymous(CreativeCategory $categoryId) : self{
-		return new self($categoryId, "");
-	}
-
-	public function getCategoryId() : CreativeCategory{
-		return $this->categoryId;
-	}
+		$result = new self();
 
-	public function setCategoryId(CreativeCategory $categoryId) : void{
-		$this->categoryId = $categoryId;
-	}
+		$result->categoryId = $categoryId;
+		$result->name = "";
+		$result->icon = null;
 
-	public function getName() : string{
-		return $this->name;
+		return $result;
 	}
 
-	public function setName(string $name) : void{
-		$this->name = $name;
-	}
+	public static function named(CreativeCategory $categoryId, Translatable|string $name, Item $icon) : self{
+		$result = new self();
 
-	public function getIcon() : ?Item{
-		return $this->icon;
-	}
+		$result->categoryId = $categoryId;
+		$result->name = $name;
+		$result->icon = $icon;
 
-	public function setIcon(?Item $icon) : void{
-		$this->icon = $icon;
+		return $result;
 	}
 }

src/network/mcpe/cache/CreativeInventoryCache.php

@@ -26,6 +26,7 @@
 use pocketmine\inventory\CreativeCategory;
 use pocketmine\inventory\CreativeInventory;
 use pocketmine\inventory\data\CreativeGroup;
+use pocketmine\lang\Translatable;
 use pocketmine\network\mcpe\convert\TypeConverter;
 use pocketmine\network\mcpe\protocol\CreativeContentPacket;
 use pocketmine\network\mcpe\protocol\types\inventory\CreativeGroupEntry;
@@ -70,22 +71,21 @@ private function buildCreativeInventoryCache(CreativeInventory $inventory) : Cre
 		$typeConverter = TypeConverter::getInstance();
 
 		$index = 0;
-		$mappedGroups = array_reduce($inventory->getItemGroup(), function (array $carry, CreativeGroup $group) use ($typeConverter, &$index, &$groups) : array{
+		$mappedGroups = array_reduce($inventory->getItemGroups(), function (array $carry, CreativeGroup $group) use ($typeConverter, &$index, &$groups) : array{
 			if (!isset($carry[$id = spl_object_id($group)])) {
 				$carry[$id] = $index++;
 
-				$categoryId = match($group->getCategoryId()){
+				$categoryId = match($group->categoryId){
 					CreativeCategory::CONSTRUCTION => CreativeContentPacket::CATEGORY_CONSTRUCTION,
 					CreativeCategory::NATURE => CreativeContentPacket::CATEGORY_NATURE,
 					CreativeCategory::EQUIPMENT => CreativeContentPacket::CATEGORY_EQUIPMENT,
 					CreativeCategory::ITEMS => CreativeContentPacket::CATEGORY_ITEMS
 				};
 
-				$groupIcon = $group->getIcon();
 				$groups[] = new CreativeGroupEntry(
 					$categoryId,
-					$group->getName(),
-					$groupIcon === null ? ItemStack::null() : $typeConverter->coreItemStackToNet($groupIcon)
+					$group->name instanceof Translatable ? $group->name->getText() : (string) $group->name,
+					$group->icon === null ? ItemStack::null() : $typeConverter->coreItemStackToNet($group->icon)
 				);
 			}
 			return $carry;
@@ -96,7 +96,7 @@ private function buildCreativeInventoryCache(CreativeInventory $inventory) : Cre
 			$items[] = new CreativeItemEntry(
 				$k,
 				$typeConverter->coreItemStackToNet($item),
-				$mappedGroups[spl_object_id($inventory->getGroup($k) ?? throw new \AssertionError("Item group not found"))]
+				$mappedGroups[spl_object_id($inventory->getItemGroupByIndex($k) ?? throw new \AssertionError("Item group not found"))]
 			);
 		}
 

tools/generate-bedrock-data-from-packets.php

@@ -291,7 +291,6 @@ public function handleItemRegistry(ItemRegistryPacket $packet) : bool{
 	public function handleCreativeContent(CreativeContentPacket $packet) : bool{
 		echo "updating creative inventory data\n";
 
-		/** @var array<int, ItemStackData[]> $groupItems */
 		$groupItems = array_reduce($packet->getItems(), function (array $carry, CreativeItemEntry $item) : array{
 			$carry[$item->getGroupId()][] = self::objectToOrderedArray($this->itemStackToJson($item->getItem()));
 			return $carry;
@@ -306,7 +305,6 @@ public function handleCreativeContent(CreativeContentPacket $packet) : bool{
 			CreativeContentPacket::CATEGORY_ITEMS => "items",
 		];
 
-		/** @var array<int, CreativeGroupData[]> $groupCategories */
 		$groupCategories = array_reduce(array_keys($packet->getGroups()), function (array $carry, int $groupIndex) use ($typeMap, $groups, $groupItems) : array{
 			$group = $groups[$groupIndex];
 			if(!isset($typeMap[$group->getCategoryId()])){