anchor.diff:          "metrics": [
             {"field": "m"},
             {"field": "i"},
  -          {"field": "d"}
  +          {"field": "d"},
  +          {"field": "t.keyword"}
           ],
           "sort": {"s": "desc"}
         }
  
positive.code:         "metrics": {
            "m": 2.718280076980591,
            "i": -12,
            "d": "2019-12-31T00:12:12.000Z"
          }
        } ]
      }
  
negative.code: `metrics` selects the fields of the "top" document to return. You can request
  a single metric with something like `"metric": {"field": "m"}` or multiple
  metrics by requesting a list of metrics like `"metric": [{"field": "m"}, {"field": "i"}`.
  The fields can be <<number,numbers>>, <<keyword,keywords>>, or <<ip,ips>>.
  Here is a more complete example:
  
  [source,console,id=search-aggregations-metrics-top-metrics-list-of-metrics]
  