public class InvBug extends JavaPlugin implements Listener
{

    Inventory inv;

    @Override
    public void onEnable()
    {

        inv = Bukkit.createInventory(null, InventoryType.DISPENSER, ChatColor.GREEN + "InvBug");

        Bukkit.getPluginManager().registerEvents(this, this);

    }

    @EventHandler(priority = EventPriority.HIGHEST)
    public void a(PlayerJoinEvent event)
    {

        event.getPlayer().openInventory(inv);

    }

}