schema.json

{
    "$schema": "http://json-schema.org/draft-07/schema#",
    "additionalProperties": false,
    "definitions": {
        "B.B": {
            "additionalProperties": false,
            "properties": {
                "b": {
                }
            },
            "required": [
                "b"
            ],
            "type": "object"
        },
        "C.C": {
            "additionalProperties": false,
            "properties": {
                "c": {
                    "$ref": "#/definitions/B.B"
                }
            },
            "required": [
                "c"
            ],
            "type": "object"
        }
    },
    "properties": {
        "d": {
            "$ref": "#/definitions/C.C"
        }
    },
    "required": [
        "d"
    ],
    "type": "object"
}