public class TelekinesisCommand implements CommandExecutor {
    public Telekinesis plugin;

    public TelekinesisCommand (Telekinesis instance) {
        plugin = instance;
    }

    @Override
    public boolean onCommand(CommandSender sender, Command command, String label, String[] args) {
        if(!(sender instanceof Player)) return false;
        Player player = (Player) sender;

        ItemStack holding = player.getInventory().getItemInMainHand();
        ItemMeta meta = holding.getItemMeta() != null ? holding.getItemMeta() : Bukkit.getItemFactory().getItemMeta(holding.getType());
        PersistentDataContainer container = meta.getPersistentDataContainer();
        String tel = container.get(new NamespacedKey(plugin, "TELEKINESIS"), PersistentDataType.STRING);
        if(tel != null) {
            player.sendMessage(ChatColor.translateAlternateColorCodes('&', "&8&b[&fTEL&8] &cYou already have Telekinesis on this item!"));
            return false;
        }

        container.set(new NamespacedKey(plugin, "TELEKINESIS"), PersistentDataType.STRING, "TRUE");
        List<String> lore = meta.getLore();
        lore.add(ChatColor.translateAlternateColorCodes('&', "&7Telekinesis I"));
        meta.setLore(lore);
        player.sendMessage(ChatColor.translateAlternateColorCodes('&', "&8&b[&fTEL&8] &7Added Telekinesis to your item!"));
        return false;
    }
}