How to convert JSON from Atlas Function(with time field) to Kotlin Object

I am trying to read data directly from atlas using a function which returns the data in JSON format. But am unable to reach the datetime value from the fetched results.

"eventTime": {
      "$date": {
"$numberLong": "1680641687263"

This is the error received : “org.json.JSONException: No value for eventTime.value”.
I am able to read all other data since they their type is a String type. I used both the JSONArray() class and Jackson Module api.