Different Skulls for Recipe?

Hello everyone,
I'm currently making a plugin that makes skulls craftable, and I'm wondering how I could specify it to be a Steve skull, Creeper skull, or Zombie skull. Here's my code:

Code:java

package me.Qisol.Flexipe;
 
import org.bukkit.Bukkit;
import org.bukkit.Material;
import org.bukkit.inventory.ItemStack;
import org.bukkit.inventory.ShapedRecipe;
import org.bukkit.plugin.java.JavaPlugin;
 
public class main extends JavaPlugin {
 
    public void onEnable() {
 
        // Skeleton Skull
        ShapedRecipe skskull = new ShapedRecipe(new ItemStack(Material.SKULL_ITEM));
        skskull.shape(new String[]{"///","/&/","///"}).setIngredient('/', Material.BONE).setIngredient('&', Material.GOLD_INGOT);
        Bukkit.getServer().addRecipe(skskull);
 
        // Zombie Skull
        ShapedRecipe zoskull = new ShapedRecipe(new ItemStack(Material.SKULL_ITEM));
        zoskull.shape(new String[]{"###","#&#","###"}).setIngredient('#', Material.ROTTEN_FLESH).setIngredient('&', Material.GOLD_INGOT);
        Bukkit.getServer().addRecipe(zoskull);
 
        // Creeper Skull
        ShapedRecipe crskull = new ShapedRecipe(new ItemStack(Material.SKULL_ITEM));
        crskull.shape(new String[]{"%%%","%&%","%%%"}).setIngredient('%', Material.SULPHUR).setIngredient('&', Material.GOLD_INGOT);
        Bukkit.getServer().addRecipe(crskull);
 
        // Wither Skull
        ShapedRecipe wiskull = new ShapedRecipe(new ItemStack(Material.SKULL_ITEM));
        wiskull.shape(new String[]{"$$$","$&$","$$$"}).setIngredient('$', Material.ENDER_PEARL).setIngredient('&', Material.GOLD_INGOT);
        Bukkit.getServer().addRecipe(wiskull);
 
        // Steve Skull
        ShapedRecipe stskull = new ShapedRecipe(new ItemStack(Material.SKULL_ITEM));
        stskull.shape(new String[]{"@@@","@&@","@@@"}).setIngredient('@', Material.APPLE).setIngredient('&', Material.GOLD_INGOT);
        Bukkit.getServer().addRecipe(stskull);
 
    }
 
    public void onDisable() {
 
        Bukkit.getServer().clearRecipes();
 
    }
}