Source code of AnimatedIronGolemSpawn (https://www.spigotmc.org/resources/106692/)

AnimatedIronGolemSpawn.java

package com.loohp.animatedirongolemspawn;

import org.bukkit.Bukkit;
import org.bukkit.ChatColor;
import org.bukkit.Location;
import org.bukkit.Material;
import org.bukkit.Particle;
import org.bukkit.Sound;
import org.bukkit.SoundCategory;
import org.bukkit.World;
import org.bukkit.block.Block;
import org.bukkit.block.BlockFace;
import org.bukkit.block.data.BlockData;
import org.bukkit.block.data.Directional;
import org.bukkit.entity.IronGolem;
import org.bukkit.entity.LivingEntity;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.EventPriority;
import org.bukkit.event.Listener;
import org.bukkit.event.entity.CreatureSpawnEvent;
import org.bukkit.plugin.Plugin;
import org.bukkit.plugin.java.JavaPlugin;

import java.util.List;
import java.util.function.Consumer;
import java.util.stream.Collectors;

public class AnimatedIronGolemSpawn extends JavaPlugin implements Listener {

    private static final BlockData IRON_BLOCK_DATA = Bukkit.createBlockData(Material.IRON_BLOCK);
    private static final BlockData PUMPKIN_DATA = Bukkit.createBlockData(Material.CARVED_PUMPKIN, d -> ((Directional) d).setFacing(BlockFace.SOUTH));

    private static final boolean FOLIA = classExist("io.papermc.paper.threadedregions.scheduler.AsyncScheduler");

    private static boolean classExist(String className) {
        try {
            Class.forName(className);
            return true;
        } catch (ClassNotFoundException e) {
            return false;
        }
    }

    public static void runTaskLater(Plugin plugin, Location location, Runnable runnable, int delay) {
        if (FOLIA) {
            //noinspection rawtypes,unchecked
            Bukkit.getRegionScheduler().runDelayed(plugin, location, (Consumer) st -> runnable.run(), delay);
        } else {
            Bukkit.getScheduler().runTaskLater(plugin, runnable, delay);
        }
    }

    @Override
    public void onEnable() {
        getServer().getPluginManager().registerEvents(this, this);
        getServer().getConsoleSender().sendMessage(ChatColor.GREEN + "AnimatedIronGolemSpawn has been enabled!");
    }

    @Override
    public void onDisable() {
        getServer().getConsoleSender().sendMessage(ChatColor.RED + "AnimatedIronGolemSpawn had been disabled!");
    }

    @EventHandler(priority = EventPriority.HIGHEST, ignoreCancelled = true)
    public void onIronGolemSpawn(CreatureSpawnEvent event) {
        LivingEntity entity = event.getEntity();
        if (entity instanceof IronGolem && event.getSpawnReason().equals(CreatureSpawnEvent.SpawnReason.VILLAGE_DEFENSE)) {
            runSpawnSequence((IronGolem) entity);
        }
    }

    public void runSpawnSequence(IronGolem ironGolem) {
        if (ironGolem.isInvisible()) {
            return;
        }
        boolean hasAI = ironGolem.hasAI();
        boolean isInvulnerable = ironGolem.isInvulnerable();
        ironGolem.setAI(false);
        ironGolem.setInvisible(true);
        ironGolem.setInvulnerable(true);
        Location location = ironGolem.getLocation();
        World world = ironGolem.getWorld();
        List<Player> players = getPlayersInRange(location);
        Block originBlock = location.getBlock();
        Block centerBlock = originBlock.getRelative(BlockFace.UP);
        Block[] ironBlocks = new Block[] {originBlock, centerBlock, centerBlock.getRelative(BlockFace.EAST), centerBlock.getRelative(BlockFace.WEST)};
        Block head = centerBlock.getRelative(BlockFace.UP);
        runTaskLater(this, location, () -> players.forEach(each -> {
            each.sendBlockChange(ironBlocks[0].getLocation(), IRON_BLOCK_DATA);
            world.playSound(ironBlocks[0].getLocation(), Sound.BLOCK_METAL_PLACE, SoundCategory.BLOCKS, 1.0F, 1.2F);
        }), 2);
        runTaskLater(this, location, () -> players.forEach(each -> {
            each.sendBlockChange(ironBlocks[1].getLocation(), IRON_BLOCK_DATA);
            world.playSound(ironBlocks[1].getLocation(), Sound.BLOCK_METAL_PLACE, SoundCategory.BLOCKS, 1.0F, 1.2F);
        }), 12);
        runTaskLater(this, location, () -> players.forEach(each -> {
            each.sendBlockChange(ironBlocks[2].getLocation(), IRON_BLOCK_DATA);
            world.playSound(ironBlocks[2].getLocation(), Sound.BLOCK_METAL_PLACE, SoundCategory.BLOCKS, 1.0F, 1.2F);
        }), 22);
        runTaskLater(this, location, () -> players.forEach(each -> {
            each.sendBlockChange(ironBlocks[3].getLocation(), IRON_BLOCK_DATA);
            world.playSound(ironBlocks[3].getLocation(), Sound.BLOCK_METAL_PLACE, SoundCategory.BLOCKS, 1.0F, 1.2F);
        }), 32);
        runTaskLater(this, location, () -> players.forEach(each -> {
            each.sendBlockChange(head.getLocation(), PUMPKIN_DATA);
            world.playSound(head.getLocation(), Sound.BLOCK_WOOD_PLACE, SoundCategory.BLOCKS, 1.0F, 0.8F);
        }), 42);
        runTaskLater(this, location, () -> {
            players.forEach(each -> {
                world.spawnParticle(Particle.BLOCK_CRACK, ironBlocks[0].getLocation().add(0.5, 0.5, 0.5), 50, IRON_BLOCK_DATA);
                world.spawnParticle(Particle.BLOCK_CRACK, ironBlocks[1].getLocation().add(0.5, 0.5, 0.5), 50, IRON_BLOCK_DATA);
                world.spawnParticle(Particle.BLOCK_CRACK, ironBlocks[2].getLocation().add(0.5, 0.5, 0.5), 50, IRON_BLOCK_DATA);
                world.spawnParticle(Particle.BLOCK_CRACK, ironBlocks[3].getLocation().add(0.5, 0.5, 0.5), 50, IRON_BLOCK_DATA);
                world.spawnParticle(Particle.BLOCK_CRACK, head.getLocation().add(0.5, 0.5, 0.5), 50, PUMPKIN_DATA);
                world.playSound(ironBlocks[0].getLocation(), Sound.BLOCK_METAL_BREAK, SoundCategory.BLOCKS, 1.0F, 1.2F);
                world.playSound(ironBlocks[1].getLocation(), Sound.BLOCK_METAL_BREAK, SoundCategory.BLOCKS, 1.0F, 1.2F);
                world.playSound(ironBlocks[2].getLocation(), Sound.BLOCK_METAL_BREAK, SoundCategory.BLOCKS, 1.0F, 1.2F);
                world.playSound(ironBlocks[3].getLocation(), Sound.BLOCK_METAL_BREAK, SoundCategory.BLOCKS, 1.0F, 1.2F);
                world.playSound(head.getLocation(), Sound.BLOCK_WOOD_BREAK, SoundCategory.BLOCKS, 1.0F, 0.8F);
                each.sendBlockChange(ironBlocks[0].getLocation(), ironBlocks[0].getBlockData());
                each.sendBlockChange(ironBlocks[1].getLocation(), ironBlocks[1].getBlockData());
                each.sendBlockChange(ironBlocks[2].getLocation(), ironBlocks[2].getBlockData());
                each.sendBlockChange(ironBlocks[3].getLocation(), ironBlocks[3].getBlockData());
                each.sendBlockChange(head.getLocation(), head.getBlockData());
                ironGolem.setAI(hasAI);
                ironGolem.setInvisible(false);
                ironGolem.setInvulnerable(isInvulnerable);
            });
        }, 44);
    }

    public List<Player> getPlayersInRange(Location location) {
        World world = location.getWorld();
        int distance = world.getSimulationDistance();
        int distanceSquared = distance * distance;
        return world.getPlayers().stream().filter(each -> each.getLocation().distanceSquared(location) < distanceSquared).collect(Collectors.toList());
    }

}