Sending asJson to an instance of Date, Time, or DateAndTime, produces an empty result in versions 3.6.x, since the actual class for most instances of these classes are SmallDate, SmallTime, or SmallDateAndTime.
With v3.7, these methods produce JSON strings with the actual printed representation, rather than the instance variable contents.
Time now asJson
3.7 and later: "11:21:52"
3.6.x: {}
earlier versions: {"milliseconds":41206025}
Date today asJson
3.7 and later: "2023-09-13"
3.6.x: {}
earlier versions: {"year":2023,"dayOfYear":256}
DateAndTime now asJson
3.7 and later: "2023-09-13T11:21:53-07:00"
3.6.x: {}
earlier versions: {"seconds":716322407.129889,"offset":-25200}
Last updated: 9/13/23