CoreClass.java

package io.github.thatsmusic99.skeletonhp;

import com.mojang.authlib.GameProfile;
import org.bukkit.Bukkit;
import org.bukkit.ChatColor;
import org.bukkit.Material;
import org.bukkit.command.Command;
import org.bukkit.command.CommandSender;
import org.bukkit.entity.Player;
import org.bukkit.inventory.ItemStack;
import org.bukkit.inventory.meta.SkullMeta;
import org.bukkit.plugin.java.JavaPlugin;

import java.lang.reflect.Field;
import java.util.Locale;
import java.util.UUID;

public class CoreClass extends JavaPlugin {

    @Override
    public void onEnable() {
        getCommand("head").setExecutor(this);
    }

    @Override
    public boolean onCommand(CommandSender sender, Command command, String label, String[] args) {
        if (args.length > 0 && sender instanceof Player) {
            ItemStack skull = new ItemStack(Material.PLAYER_HEAD);
            SkullMeta meta = (SkullMeta) skull.getItemMeta();

            switch (args[0].toLowerCase(Locale.ROOT)) {
                case "setowner":
                    meta.setOwner("Thatsmusic99");
                    break;
                case "setowning":
                    meta.setOwningPlayer(Bukkit.getOfflinePlayer("Thatsmusic99"));
                    break;
                case "headsplus":
                    meta = setSkullOwner("Thatsmusic99", meta);
                    break;
                default:
                    return true;
            }
            meta.setDisplayName(ChatColor.translateAlternateColorCodes('&', "&e:)"));
            skull.setItemMeta(meta);
            ((Player) sender).getInventory().addItem(skull);
        }
        return true;
    }

    private SkullMeta setSkullOwner(String s, SkullMeta m) {
        UUID uuid;
        if (Bukkit.getPlayer(s) != null) {
            uuid = Bukkit.getPlayer(s).getUniqueId();
        } else {
            uuid = UUID.nameUUIDFromBytes(s.getBytes());
        }
        GameProfile profile = new GameProfile(uuid, s);
        try {
            Field profileField = m.getClass().getDeclaredField("profile");
            profileField.setAccessible(true);
            profileField.set(m, profile);
        } catch (NoSuchFieldException | IllegalAccessException e) {
            e.printStackTrace();
        }
        return m;
    }
}