Error

package tutorial;

import org.bukkit.Bukkit;
import org.bukkit.ChatColor;
import org.bukkit.command.Command;
import org.bukkit.command.CommandSender;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.player.PlayerJoinEvent;
import org.bukkit.event.player.PlayerQuitEvent;
import org.bukkit.plugin.java.JavaPlugin;

/**
 *
 * @author Lucas
 */
public class Tutorial extends JavaPlugin implements Listener {

    @Override
    public void onEnable() {
        Bukkit.getConsoleSender().sendMessage("§3[§aTutorial§3]§f Plugin habilitado com sucesso !");
        Bukkit.getPluginManager().registerEvents(this, this);
    }

    @Override
    public void onDisable() {
        Bukkit.getConsoleSender().sendMessage("§3[§aTutorial§3]§f Plugin desabilitado com sucesso !");
    }

@EventHandler
    public void OnJoin(PlayerJoinEvent e) {
        e.setJoinMessage(null);
        Bukkit.broadcastMessage("§3[§a+§3] §f"+e.getPlayer().getName());

    }

@EventHandler
    public void onQuit(PlayerQuitEvent e) {
    e.setQuitMessage(null);
       Bukkit.broadcastMessage("§3[§c-§3] §f"+e.getPlayer().getName());
    }

    @Override
    public boolean onCommand(CommandSender sender, Command command, String label, String[] args) {

        if (sender instanceof Player){
            if (command.getName().equalsIgnoreCase("send"));{
                sender.sendMessage(ChatColor.GREEN+"Você enviou uma mensagem");
        }
            if (command.getName().equalsIgnoreCase("Heal")){
                Player player = (Player) sender;
                if (player.getHealth()<20){
                    player.setHealth(20);
                    player.sendMessage(ChatColor.GREEN+"Você foi curado.");
                } else {
                    player.sendMessage(ChatColor.GREEN+"Você não precisa ser curado.");
                }
            }



        }




        return false;
    }



}