I'm trying to figure out how to add a seed ("long seed") to this function:

LevelStem createLevel(MinecraftServer server, ResourceKey<Level> levelType, long seed)
    {
        if (levelType == Level.OVERWORLD) {
            ServerLevel oldLevel = server.getLevel(Level.OVERWORLD);
        } else if (levelType == Level.NETHER) {
            ServerLevel oldLevel = server.getLevel(Level.NETHER);
        } else if (levelType == Level.END) {
            ServerLevel oldLevel = server.getLevel(Level.END);
        } else {
            throw new CommandRuntimeException(Component.literal(String.format("Error copying dimension: %s", "Only the overworld, nether, and end are supported")));
        }
        ServerLevel oldLevel = server.overworld();
        DynamicOps<Tag> ops = RegistryOps.create(NbtOps.INSTANCE, server.registryAccess());
        ChunkGenerator oldChunkGenerator = oldLevel.getChunkSource().getGenerator();
        ChunkGenerator newChunkGenerator = ChunkGenerator.CODEC.encodeStart(ops, oldChunkGenerator)
                .flatMap(nbt -> ChunkGenerator.CODEC.parse(ops, nbt))
                .getOrThrow(false, s ->
                {
                    throw new CommandRuntimeException(Component.literal(String.format("Error copying dimension: %s", s)));
                });


        Holder<DimensionType> typeHolder = oldLevel.dimensionTypeRegistration();
//        newChunkGenerator.withSeed(server.getLevel(Level.OVERWORLD).getSeed()); DOES NOT WORK
        return new LevelStem(typeHolder, newChunkGenerator);
    }

I could have used ChunkGenerator#withSeed(long seed) in 1.16/1.17, but where did it move to for 1.19? If It was removed, how do I mimic this functionality?

Found WorldGenSettings#withSeed(bool, OptionalLong), but still struggling to implement it into the function.