content: {
    "$defs": {
      "Signature": {
        "description": "JSON Web Signature in compact form.",
        "title": "Signature",
        "type": "string"
      }
    },
    "$id": "https://gobl.org/draft-0/dsig/signature",
    "$ref": "#/$defs/Signature",
    "$schema": "https://json-schema.org/draft/2020-12/schema"
  }