PathFacts

What the schema declares at one path. Each field is None when the schema leaves it
unconstrained, so an absent field never reads as "nothing is admitted".

{
    "items": {
        "types": [
            "null"
        ],
        "values": [
            null
        ]
    },
    "types": [
        "null"
    ],
    "values": [
        null
    ]
}