Nested text fields aggregation query requests return 400

For nested search, aggregation for text fields returns 400.

Example:

{
  "kind": "osdu:wks:master-data--Wellbore:1.0.0",
  "aggregateBy": "nested(data.VerticalMeasurements, VerticalMeasurementSourceID)", 
  "limit": 1
}

Response:

{
  "code": 400,
  "reason": "Bad Request",
  "message": "Aggregations are not supported for one or more of the specified fields"
}