MultiLineString can not be displayed in Web-viewer

[FiiScho]

I want to study how to create a CityJSON file for MultiLineString with simple code:

{
    "type": "CityJSON",
    "version": "2.0",
    "transform": {
        "scale": [1.0, 1.0, 1.0],
        "translate": [0.0, 0.0, 0.0]
    },
    "CityObjects": {
        "id_1": {
            "type": "OtherConstruction",
            "geometry": [
                {
                    "type": "MultiLineString",
                    "lod": "1.0",
                    "boundaries": [
                        [0, 1, 2]
                    ]
                }
            ]
        }
    },
    "vertices": [[0, 0, 0], [1, 2, 1], [2, 2, 2]]
}

I dropped this file into https://ninja.cityjson.org/, but it displayed nothing. It worked, if I replaced the MultiLineString with MultiPoint or MultiSurface, and changed the depth of array for boundaries relatively. So how could I do?