minecraft-assets/assets/minecraft/blockstates/structure_void.json

{
    "variants": {
        "normal": [
            { "model": "structure_void" },
            { "model": "structure_void", "y": 90 },
            { "model": "structure_void", "y": 180 },
            { "model": "structure_void", "y": 270 }
        ]
    }
}