Promtail to parse all available objects in nested JSON array for Grafana Loki

I have some JSON which I am looking to parse with a pipeline stage. I have defined expressions and created a new JSON stage for every nested object/array, however the logs that I am parsing do not have a definite number of objects in an array. It could be 2, it could be 5.

Here is some example JSON

{
  "level": "info",
  "msg": "This is the message",
  "stats": {
    "bytes": 12345,
    "checks": 1234,
    "transferring": [
      {
        "eta": 1234,
        "name": "path/to/file/1"
      },
      {
        "eta": 1234,
        "name": "path/to/file/2"
      },
      {
        "eta": 1234,
        "name": "path/to/file/3"
      },
      {
        "eta": 1234,
        "name": "path/to/file/4"
      },
      {
        "eta": 1234,
        "name": "path/to/file/5"
      }
    ],
    "transfers": 28
  },
  "time": "2022-07-28T13:55:47.251259+01:00"
}

Here is my pipeline_stage:

pipeline_stages:
    - json:
        expressions:
          level: level
          msg: msg
          timestamp: time
          stats:
    - json:
        expressions:
          bytes: bytes
          checks: checks
          transferring:
        source: stats
    - json:
        expressions:
          transferring_eta: eta
          transferring_name: name
        source: transferring
    - labels:
        level:
        msg:
        timestamp:
        stats:
        bytes:
        checks:
        transferring:
        transferring_eta:
        transferring_name:

The “bytes” and “checks” key-value pairs get created, as they are nested inside the “stats” value, however I can not create the “transferring_eta” or “transferring_name” key-value pairs.