{
  "$ref": "#/$defs/SchemaRoot",
  "$defs": {
    "SchemaRoot": {
      "properties": {
        "a": {
          "$ref": "#/$defs/SchemaRootA"
        }
      },
      "type": "object"
    },
    "SchemaRootA": {
      "properties": {
        "b": {
          "$ref": "#/$defs/SchemaRoot"
        }
      },
      "type": "object"
    }
  }
}