JED - Secondary (imported?) overworld

{
    "dimensions": [
        {
            "dim": 123,
            "dimensiontype": {
                "id": 123,
                "name": "Second Overworld",
                "suffix": "_dim123",
                "keeploaded": false,
                "worldprovider": "WorldProviderSurfaceJED"
            },
            "worldinfo_onetime": {
                "generatorName": "default",
                "RandomSeed": 12345
            }
        }
    ]
}