Plugin.java

private void moveBitch( final Location start, final ArrayList<Tile> tiles, final Callback<Void> callback ) {
        final AtomicInteger curPos = new AtomicInteger( 0 );
        final Plugin plugin = this;

        final Runnable moveRunnable = new Runnable() {
            @Override
            public void run() {
                if (skeleton1 != null) {
                    int current = curPos.getAndAdd( 1 );

                    if ( current >= tiles.size() ) {
                        Bukkit.getScheduler().scheduleSyncDelayedTask( plugin, new Runnable() {
                            @Override
                            public void run() {
                                callback.done( null );
                            }
                        }, ((Double) ( Math.random() * (double) 60 )).intValue() );

                        return;
                    }

                    Tile tile = tiles.get( current );
                    Location location1 = tile.getLocation( start ).add( 0, 1, 0 );

                    ((CraftSkeleton) skeleton1).getHandle().setLocation( location1.getX(), location1.getY(), location1.getZ(), location1.getYaw(), location1.getPitch() );

                    Bukkit.getScheduler().scheduleSyncDelayedTask( plugin, this, 5 );
                }
            }
        };

        Bukkit.getScheduler().scheduleSyncDelayedTask( this, moveRunnable, 5 );
    }