Heal command:
package com.bloody.plugin;

import org.bukkit.command.Command;
import org.bukkit.command.CommandExecutor;
import org.bukkit.command.CommandSender;
import org.bukkit.entity.Player;

import net.md_5.bungee.api.ChatColor;

public class HealCommand implements CommandExecutor{

	private Main main;

	public HealCommand() {


		this.main = main;
	}
	@Override
	public boolean onCommand(CommandSender sender, Command cmd, String label, String[] args) {
		Player player = (Player) sender;
		if (player.hasPermission("testplugin.heal")) {
			player.sendMessage(ChatColor.translateAlternateColorCodes('&', this.main.getConfig().getString("ServerName" + "HealMessage")));
			player.setHealth(20.0);
		}
		return false;
	}
}



Main:
package com.bloody.plugin;

import org.bukkit.ChatColor;
import org.bukkit.command.Command;
import org.bukkit.command.CommandExecutor;
import org.bukkit.command.CommandSender;
import org.bukkit.entity.Player;
import org.bukkit.plugin.java.JavaPlugin;

public class Main extends JavaPlugin implements CommandExecutor{

	@Override
	public void onEnable() {
		System.out.println("Test Plugin for bubble enabled");
		this.getConfig().options().copyDefaults();
		saveDefaultConfig();
		getCommand("heal").setExecutor(new HealCommand());

	}

	@Override
	public void onDisable() {
		System.out.println("Test Plugin for bubble disabled");
	}

}