MenuAPI

Usage:

ItemMenuInstance instance = new ItemMenuInstance("Some Menu", 18); 
instance.setButton(0, Material.GOLD_BLOCK, "Some Button", (player, menu_instance) -> { 
  player.sendMessage("LMAO"); 
}); 

// open the menu 
ItemMenu menus = MenuAPIPlugin.getInstance().getMenus(); 
menus.open(Bukkit.getPlayer("Some_Player"), instance);