@Nonnull
    @Override
    public CitizensNpc spawnNpc(@Nonnull Location location, @Nonnull String nametag, @Nonnull String skinPlayer) {
        return spawnNpc(location.clone(), nametag, npc -> npc.setSkin(skinPlayer));
    }
Implementation of {@link NpcFactory} using Citizens.
helper/src/main/java/me/lucko/helper/npc/CitizensNpcFactory.java