{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "title": "Signature",
  "description": "User signature.",
  "properties": {
    "image": {
      "$ref": "#/components/schemas/Image",
      "description": "Optional. An image of the user's signature."
    },
    "metadata": {
      "additionalProperties": {
        "type": "string"
      },
      "description": "Optional. Metadata associated with the user's signature. For example, the user's name or the user's title.",
      "type": "object"
    },
    "signatureTime": {
      "description": "Optional. Timestamp of the signature.",
      "format": "google-datetime",
      "type": "string"
    },
    "userId": {
      "description": "Required. User's UUID provided by the client.",
      "type": "string"
    }
  },
  "type": "object"
}