Stone

World world = (World)Bukkit.getWorlds().get(0);
	    Location spawnLoc = new Location(world, 0.0D, 0.0D, 0.0D);
	    world.getChunkAt(spawnLoc).load(true);
	    world.setDifficulty(Difficulty.HARD);
	    spawnLoc.setY(world.getHighestBlockYAt(0, 0) + 36);
	    world.setSpawnLocation(spawnLoc.getBlockX(), spawnLoc.getBlockY(), spawnLoc.getBlockZ());
	    for (int x = -7; x <= 7; x++) {
	      for (int y = -1; y <= 0; y++) {
	        for (int z = -7; z <= 7; z++) {
	          if ((y == -1) && (z != -7) && (z != 7) && (x != -7) && (x != 7))
	          {
	            Block block = spawnLoc.clone().add(x, y, z).getBlock();
	            block.setType(Material.STONE);
	            block.setData(DyeColor.WHITE.getWoolData());
	          }
	          else if (((y == 0) && (z == 7)) || (z == -7) || (x == 7) || (x == -7))
	          {
	            Block block = spawnLoc.clone().add(x, y, z).getBlock();
	            block.setType(Material.BARRIER);
	            block.getRelative(BlockFace.UP).setType(Material.BARRIER);
	          }
	        }
	      }