sql/connect/common/src/test/resources/query-tests/queries/relation_extension.json

{
  "common": {
    "planId": "1"
  },
  "extension": {
    "@type": "type.googleapis.com/spark.connect.ExamplePluginRelation",
    "input": {
      "common": {
        "planId": "0"
      },
      "localRelation": {
        "schema": "struct\u003cid:bigint,a:int,b:double\u003e"
      }
    }
  }
}