For v2.3, the items array includes the additional attributes below:

AttributeTypeDescription
errorobjectIndicates the “type” of error and associated “status” that prevented the speaker from initiating or interrupting playback. See SMAPI error objects page for details.
reportIdstringThis is a stable UUID in the canonical format that you may use to correlate periodic and final reports for a single logical track playback. Unlike the id field, this identifier changes on each logical playback of the track queue item. For example, you can use this attribute to differentiate reports for id 0 when Sonos plays a different item in between, such as when a user skips back to item id 0.

Example

Final event with reportId:

{
  "items":[
    {
      "reportId":"0e5614b9-fcc7-4eec-b087-1892b7e64fa6",
      "id":"this_is_the_cloud_queue_item_id",
      "mediaUrl":"http://media.host.example.com/path/12345.mp3",
      "queueVersion":"xyz",
      "contextVersion":"abc",
      "type":"final",
      "positionMillis":500,
      "positionMillisAtSegmentStart":0,
      "durationPlayedMillis":500,
      "timeSincePlaybackMillis":1250
    }
  ]
}