public class BoxBlockEntity extends BlockEntity implements ExtendedScreenHandlerFactory, ImplementedInventory {
    private final DefaultedList<ItemStack> inventory = DefaultedList.ofSize(9, ItemStack.EMPTY);

    public BoxBlockEntity() {
        super(Test.BOX_BLOCK_ENTITY);
    }


    //From the ImplementedInventory Interface

    @Override
    public DefaultedList<ItemStack> getItems() {
        return inventory;

    }

    //These Methods are from the NamedScreenHandlerFactory Interface

    @Override
    public @Nullable ScreenHandler createMenu(int syncId, PlayerInventory playerInventory, PlayerEntity player) {
        //We provide this to the screenHandler as our class Implements Inventory
        //Only the Server has the Inventory at the start, this will be synced to the client in the ScreenHandler
        return new BoxScreenHandler(syncId, playerInventory, this);
    }

    @Override
    public Text getDisplayName() {
        // versions 1.18 and below
        return new TranslatableText(getCachedState().getBlock().getTranslationKey());
        
        // versions 1.19 and later
        return Text.translatable(getCachedState().getBlock().getTranslationKey());
    }

    //This Method is from the ExtendedScreenHandlerFactory

    //This method gets called on the Server when it requests the client to open the screenHandler.
    //The contents you write into the packetByteBuf will automatically be transferred in a packet to the client
    //and the ScreenHandler Constructor with the packetByteBuf argument gets called on the client
    //
    //The order you insert things here is the same as you need to extract them. You do not need to reverse the order!
    @Override
    public void writeScreenOpeningData(ServerPlayerEntity serverPlayerEntity, PacketByteBuf packetByteBuf) {
        //The pos field is a public field from BlockEntity
        packetByteBuf.writeBlockPos(pos);
    }
}