handle json reference in json schema

[yuhao-su]

It's a common practice in JSON schema that a field refers to content in a definition to define its properties.

https://json-schema.org/draft/2020-12/draft-bhutton-json-schema-00#rfc.section.8.2.3

https://json-schema.org/understanding-json-schema/structuring#dollarref

{
    "name": "example",
    "address": { "$ref": "#/definitions/address" },
    "definitions": {
        "address": {
            "city": "Austin",
            "state": "TX"
        }
    }
}