World generation

public final class RoadWorldGenerator implements IWorldGenerator
{
    private static final Material[] allowedMaterials = new Material[]
    { Material.CLAY, Material.GRASS, Material.GROUND, Material.ICE, Material.PACKED_ICE, Material.SAND, Material.SNOW };

    private static boolean materialIsAllowed(Material material)
    {
        for(Material i : allowedMaterials)
            if(material == i)
                return true;

        return false;
    }

    @Override
    public void generate(Random          random,
                         int             chunkX,
                         int             chunkZ,
                         World           world,
                         IChunkGenerator chunkGenerator,
                         IChunkProvider  chunkProvider)
    {
        RoadMap roadmap = RoadMapRegistry.get(world.provider.getDimension());

        if(roadmap == null)
            return;

        int blockX = chunkX * 16;
        int blockZ = chunkZ * 16;
        Set<BlockPos> blockPositions = new HashSet<BlockPos>();

        for(int x = blockX; x < (blockX + 16); x++)
            for(int z = blockZ; z < (blockZ + 16); z++)
            {
                if(!roadmap.getAt(x, z))
                    continue;

                blockPositions.addAll(RoadStyle.grassy.getRoadBlocks(new BlockPos(x, 255, z)));
            }

        for(BlockPos i : blockPositions)
        {
            BlockPos topBlock = world.getTopSolidOrLiquidBlock(i).down();

            if(!materialIsAllowed(world.getBlockState(topBlock).getMaterial()))
                continue;

            RoadStyle.grassy.drawRoadBlockAt(world, topBlock);
        }
    }
}