Help with a minecraft pluginlocation_city

Hi my friend needs help with his new plugin which can make him transform into a dragon, it will be on my server World Colony but we are having issues running the plugin on the server I need a corrected version of the code that could run.

package com.example.dragoneye;

import org.bukkit.Material;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.player.PlayerInteractEvent;
import org.bukkit.inventory.ItemStack;
import org.bukkit.plugin.java.JavaPlugin;
import org.bukkit.scheduler.BukkitRunnable;

public class DragonEyePlugin extends JavaPlugin implements Listener {

private static final ItemStack ENDER_EYE = new ItemStack(Material.ENDER_EYE, 1); // Change material if necessary
private static final int MAX_DRAGON_USES = 5;

private int dragonUses = 0;
private boolean isDragon = false;

@Override
public void onEnable() {
getServer().getPluginManager().registerEvents(this, this);
}

@EventHandler
public void onPlayerInteract(PlayerInteractEvent event) {
Player player = event.getPlayer();
if (event.getItem() != null && event.getItem().isSimilar(ENDER_EYE)) {
if (isDragon) {
player.sendMessage("You are already a dragon!");
return;
}

dragonUses++;
if (dragonUses >= MAX_DRAGON_USES) {
isDragon = true;
player.sendMessage("You are now a dragon forever!");
} else {
player.sendMessage("You are now a dragon for 1 minute!");

// Set player as a dragon for 1 minute
isDragon = true;
new BukkitRunnable() {
@Override
public void run() {
isDragon = false;
player.sendMessage("You are no longer a dragon!");
}
}.runTaskLater(this, 20 * 60);
}
}
}