anchor.diff:  [source,console]
   ----
   PUT my-index
  +{
     "mappings": {
       "properties": {
         "my-agg-metric-field": {
           "type": "aggregate_metric_double",
  -        "metrics": [ "min", "max", "sum", "value_count"],
  +        "metrics": [ "min", "max", "sum", "value_count" ],
           "default_metric": "max"
         }
       }
     }
   }
   ----
  -// TEST[skip:awaiting fix]
   
   [[aggregate-metric-double-params]]
   ==== Parameters for `aggregate_metric_double` fields
  
positive.code: Default metric sub-field to use for queries, scripts, and aggregations that
  don't use a sub-field. Must be a value from the `metrics` array.
  
  
  [[aggregate-metric-double-uses]]
  ==== Uses
  
  
negative.code: and `value_count` metrics. To run an `avg` aggregation, the field must contain
  both `sum` and `value_count` metric sub-field.
  
  If you use an `aggregate_metric_double` field with other aggregations, the field
  uses the `default_metric` value, which behaves as a `double` field. The
  `default_metric` is also used in scripts and the following queries:
  