IllusionTheDev

import org.bukkit.Color;
import org.bukkit.Material;

public enum GlassColor {
    RED(Material.RED_STAINED_GLASS_PANE, Color.fromARGB(0x00FF0000)),
    ORANGE(Material.ORANGE_STAINED_GLASS_PANE, Color.fromARGB(0x00FFA500)),
    YELLOW(Material.YELLOW_STAINED_GLASS_PANE, Color.fromARGB(0x00FFFF00)),
    LIME(Material.LIME_STAINED_GLASS_PANE, Color.fromARGB(0x0000FF00)),
    GREEN(Material.GREEN_STAINED_GLASS_PANE, Color.fromARGB(0x00008000)),
    CYAN(Material.CYAN_STAINED_GLASS_PANE, Color.fromARGB(0x0000FFFF)),

IllusionTheDev

public class DirectImmutableHolder<T> implements Holder<T> {

    private final T value;

    private DirectImmutableHolder(T value) {
        this.value = value;
    }

    public static <T> Holder<T> of(T value) {
        return new DirectImmutableHolder<>(value);