how do I specify the name of the array of values to be buckets which is what elasticsearch returns in the results

gistfile1.txt

/*
 *   The only difference is that the name of the array is "buckets" instead of "values"
 *   When the name is "values" it works. 
 *   When the name is "buckets" it does not.
 *   I need to tell the "domain" to use "buckets" not "values", but I could not figure out how.
 */
 
{
  "$schema":"https://vega.github.io/schema/vega/v3.json",
  "width": 400, "height": 100,
  
  "data": 
    [
      { "name": "aggregations",
        "buckets": 
           [
             {"key": "metrics_collection_failed",   "doc_count": 12},
             {"key": "power supply failure",        "doc_count": 13},
             {"key": "storage controller failure",  "doc_count": 16},
             {"key": "device restarted",            "doc_count": 21},
             {"key": "driver corrupted",            "doc_count": 73}
           ]
       } 
    ],

 format: { property: "data.aggregations.buckets" },    

  "scales": [
    {
      "name": "yscale",
      "type": "linear",
      "zero": true,
      "domain": {"data": "aggregations", "field": "doc_count"},
      "range": "height"
    },
    {
      "name": "xscale",
      "type": "band",
      "domain": {"data": "aggregations",  "field": "key"},
      "range": "width",
      "padding": 0.05
    }
  ],
  
   "marks": [ {
    "type": "rect",
    "from": { "data": "aggregations" },
    "encode": {
      "update": {
        "x":     {"scale": "xscale", "field": "key"},
        "width": {"scale": "xscale", "band": 1},
        "y":     {"scale": "yscale", "field": "doc_count"},
        "y2":    {"scale": "yscale", "value": 0}
      }
    }
  } ]

 
}