ShulkersTestPlugin.java

    private boolean cancelImpacts;

    @Listener
    public void onInit(GameInitializationEvent event) {
        Sponge.getCommandManager().register(this, CommandSpec.builder().executor((src, args) -> {
            ((Player) src).getNearbyEntities(20).forEach(entity -> {
                if (entity instanceof ShulkerBullet) {
                    entity.offer(Keys.TARGETED_ENTITY, Optional.empty());
                }
            });

            return CommandResult.success();
        }).build(), "untarget");

        Sponge.getCommandManager().register(this, CommandSpec.builder().executor((src, args) -> {
            this.cancelImpacts = !this.cancelImpacts;

            return CommandResult.success();
        }).build(), "toggle_impacts");

        Sponge.getCommandManager().register(this, CommandSpec.builder().executor((src, args) -> {
            Iterator<Entity> iterator = ((Player) src).getNearbyEntities(entity -> entity instanceof Shulker).iterator();
            if (iterator.hasNext()) {
                Shulker shulker = (Shulker) iterator.next();
                World world = shulker.getWorld();
                Random random = new Random();
                // Creates the zombie in a random location within a 10x5x10 zone around the bullet
                Entity zombie = world.createEntity(EntityTypes.ZOMBIE, shulker.getLocation().add(
                        random.nextInt(20) - 10,
                        random.nextInt(5),
                        random.nextInt(20) - 10).getPosition());
                zombie.offer(Keys.POTION_EFFECTS, Arrays.asList(PotionEffect.of(PotionEffectTypes.FIRE_RESISTANCE, 255, 9999)));
                world.spawnEntity(zombie);

                shulker.launchWithTarget(ShulkerBullet.class, zombie);
            }

            return CommandResult.success();
        }).build(), "launch");
    }

    @Listener
    public void onEntitySpawn(SpawnEntityEvent event) {
        event.getEntities().forEach(entity -> {
            if (entity instanceof Shulker) {
                Collection<DyeColor> dyeColors = Sponge.getRegistry().getAllOf(DyeColor.class);
                DyeColor dyeColor = dyeColors.toArray(new DyeColor[]{})[new Random().nextInt(dyeColors.size())];
                entity.offer(Keys.DYE_COLOR, dyeColor);
            }
        });
    }

    @Listener
    public void onBlockImpact(CollideBlockEvent.Impact event) {
        if (this.cancelImpacts)
            event.setCancelled(true);
    }

    @Listener
    public void onEntityImpact(CollideEntityEvent.Impact event) {
        if (this.cancelImpacts)
            event.setCancelled(true);
    }