如何在dataweave 2上groupBy和map在同一变换？

%dw 2.0
output application/json

var inputData = [
  {
    "name": "John",
    "age": 25,
    "city": "New York"
  },
  {
    "name": "Jane",
    "age": 30,
    "city": "London"
  },
  {
    "name": "Bob",
    "age": 25,
    "city": "New York"
  }
]

var groupedData = inputData groupBy $.age

var transformedData = groupedData mapObject {
  ($$): {
    "count": size($),
    "people": $
  }
}

---
transformedData

{
  "25": {
    "count": 2,
    "people": [
      {
        "name": "John",
        "age": 25,
        "city": "New York"
      },
      {
        "name": "Bob",
        "age": 25,
        "city": "New York"
      }
    ]
  },
  "30": {
    "count": 1,
    "people": [
      {
        "name": "Jane",
        "age": 30,
        "city": "London"
      }
    ]
  }
}