Nested Aggregation in a Transforms Script

Elastic Stack Elasticsearch
1

I am trying to apply a filter in a Transform Script and map the results to a new list. I am able to successfully do this when only using 1 aggregation. However, I am not having any luck using a second aggregation that exists inside the first one. The specific part of the script that isn't working is when I try to map values to new fields. Are there any examples of how to apply filters in a watcher that is using multiple aggregations ?

"transform": {
    "script": {
      "source": "ctx.payload.aggregations.image_agg.buckets.stream().filter(a -> a.parentimage_agg.buckets.stream().filter(b -> b.doc_count > ctx.metadata.condition_count)).map(b -> ['image':b.key,'count':b.doc_count]).collect(Collectors.toList());",
      "lang": "painless"
    }
  }

I am also including a snippet of the result output. Ultimately, I am trying to alert only on specific events using doc_count in parentimage_agg.buckets and want to map that doc_count to a list, as well as the key from both aggregations.

"aggregations": {
          "image_agg": {
            "doc_count_error_upper_bound": 39,
            "sum_other_doc_count": 1882,
            "buckets": [
              {
                "doc_count": 12830,
                "parentimage_agg": {
                  "doc_count_error_upper_bound": 0,
                  "sum_other_doc_count": 0,
                  "buckets": [
                    {
                      "doc_count": 12830,
                      "key": "C:\\Program Files\\Amazon\\SSM\\amazon-ssm-agent.exe"
                    }
                  ]
                },
                "key": "C:\\Windows\\System32\\wbem\\WMIC.exe"
              }
2

if you want to access the doc_count and key fields inside of the parentimage_agg aggregation, you have to loop through all the buckets a second time inside of your map statement and then decide what you want to do with the data, if there are two buckets with the same keys