JED 1.6.0+ - Basic Void dimension

{
    "dimensions": [
        {
            "dim": 8,
            "dimensiontype": {
                "id": 8,
                "name": "Void World",
                "suffix": "_dim8",
                "keeploaded": false,
                "worldprovider": "WorldProviderSurfaceJED",
                "require_exact_match": true
            },
            "worldinfo_onetime": {
                "generatorName": "flat",
                "generatorOptions": "3;minecraft:air;127;"
            }
        }
    ]
}