Chunk test code for a "problem"

package de.seadragon91.chunktesting;

import java.util.Random;

import org.bukkit.GameMode;
import org.bukkit.Location;
import org.bukkit.Material;
import org.bukkit.World;
import org.bukkit.WorldCreator;
import org.bukkit.command.Command;
import org.bukkit.command.CommandSender;
import org.bukkit.entity.Player;
import org.bukkit.generator.ChunkGenerator;
import org.bukkit.plugin.java.JavaPlugin;
import org.bukkit.scheduler.BukkitRunnable;

public class ChunkTesting extends JavaPlugin {

        /*
         * Problem: Regenerating a chunk in a air world at players location, doesn't send the player an chunk update.
         * Using the method refreshChunk() from class world should send to all players the chunk, but it doesn't work.
         *
         * By running the command /chunktesting. This steps will be occur.
         * 1) Generates a air world.
         * 2) Teleports the player to the air world.
         * 3) Generates a cube of stone to see the the dark and have a place for placing blocks.
         * 4) Regenerate the chunk at players location, will remove stone the chunk will be then dark.
         *
         * Now try to fly to the wall and try to place blocks against the wall, they don't appear.
         * Disconnect and reconnect and you should see your "placed" blocks.
         *
         */

        @Override
        public void onDisable() {
                this.getLogger().info("disabled");
        }

        @Override
        public void onEnable() {
                this.getLogger().info("enabled.");
        }

        // returns a chunk generator full with air
        class AirChunkGenerator extends ChunkGenerator {

                @Override
                public byte[] generate(World world, Random random, int cx, int cz) {
                        return new byte[65536];
                }
        }

        @Override
        public boolean onCommand(CommandSender sender, Command command, String label, String[] args) {

                if (!command.getName().equalsIgnoreCase("chunktesting"))
                        return false;

                if (!(sender instanceof Player)) {
                        sender.sendMessage("[ChunkTesting] This command doesn't work from the console.");
                        return true;
                }

                final Player player = (Player) sender;

                // set players gamemode to creative
                player.setGameMode(GameMode.CREATIVE);

                // set player flying to true
                player.setFlying(true);

                // create air world
                final World airWorld = this.getServer().createWorld(WorldCreator.name("chunktesting").generator(new AirChunkGenerator()));

                // create a cube of stone at 0 0 0
                for (int x = 0; x < 30; x++) {
                        for (int y = 0; y < 30; y++) {
                                for (int z = 0; z < 30; z++) {
                                        airWorld.getBlockAt(x, y, z).setType(Material.STONE);
                                }
                        }
                }

                // teleport player to the top of the cube
                player.teleport(new Location(airWorld, 5, 33, 5));

                player.sendMessage("[ChunkTesting] Please wait 5s...");

                // schedule snyc delayed task for 5s
                this.getServer().getScheduler().scheduleSyncDelayedTask(this, new BukkitRunnable() {

                        @Override
                        public void run() {

                                // regenerate the chunk at players location
                                airWorld.regenerateChunk(player.getLocation().getChunk().getX(), player.getLocation().getChunk().getZ());

                                // refresh the chunk at players location
                                airWorld.refreshChunk(player.getLocation().getChunk().getX(), player.getLocation().getChunk().getZ());

                                player.sendMessage("[ChunkTesting] Now try to place blocks against the wall.");
                        }
                }, 100L);

                return true;
        }
}