[[ "CalendarEvent/set", {
  "accountId": "a0x9",
  "update": {
    "123": {
      "recurrenceOverrides/2025-03-05T09:00:00/\
        participants~1em9lQGZvb2GFtcGxlLmNvbQ~1participationStatus":
          "declined"
    }
  }
}, "0" ]]