Subscribe to updates

{
  "type": "object",
  "properties": {
    "Last-Event-ID": {
      "type": "string"
    },
    "topic": {
      "type": "array",
      "items": {
        "type": "string"
      }
    }
  },
  "required": [
    "topic"
  ],
  "additionalProperties": false
}