JED 1.6.0+ - Void dimension with no mob spawning

{
    "dimensions": [
        {
            "dim": 8,
            "normal_biomes": true,
            "dimensiontype": {
                "id": 8,
                "name": "Void Dimension",
                "suffix": "_dim8",
                "keeploaded": false,
                "worldprovider": "WorldProviderSurfaceJED",
                "require_exact_match": true
            },
            "worldinfo_onetime": {
                "generatorName": "flat",
                "generatorOptions": "3;minecraft:air;127;",
                "DayTime": 6000,
                "GameRules": {
                    "doMobSpawning": "false"
                }
            },
            "jed": {
                "CanSpawnHostiles": false,
                "CanSpawnPeacefulMobs": false
            }
        }
    ]
}