anchor.diff:  --------------------------------------------------
   {
      "_shards": {
  -      "total": 1,
  -      "successful": 1,
  +      "total": 10,
  +      "successful": 10,
         "failed": 0
      },
      "indices": {
  -      "_all": { <1>
  +      "_all": {    <1>
            "fields": {
  -            "creation_date": {
  -               "max_doc": 1326564,
  -               "doc_count": 564633,
  -               "density": 42,
  -               "sum_doc_freq": 2258532,
  -               "sum_total_term_freq": -1,
  -               "min_value": "2008-08-01T16:37:51.513Z",
  -               "max_value": "2013-06-02T03:23:11.593Z",
  -               "is_searchable": "true",
  -               "is_aggregatable": "true"
  -            },
  -            "display_name": {
  -               "max_doc": 1326564,
  -               "doc_count": 126741,
  -               "density": 9,
  -               "sum_doc_freq": 166535,
  -               "sum_total_term_freq": 166616,
  -               "min_value": "0",
  -               "max_value": "정혜선",
  -               "is_searchable": "true",
  -               "is_aggregatable": "false"
  -            },
  -            "answer_count": {
  -               "max_doc": 1326564,
  -               "doc_count": 139885,
  -               "density": 10,
  -               "sum_doc_freq": 559540,
  -               "sum_total_term_freq": -1,
  -               "min_value": 0,
  -               "max_value": 160,
  -               "is_searchable": "true",
  -               "is_aggregatable": "true"
  -            },
  -            "rating": {
  -               "max_doc": 1326564,
  -               "doc_count": 437892,
  -               "density": 33,
  -               "sum_doc_freq": 1751568,
  -               "sum_total_term_freq": -1,
  -               "min_value": -14,
  -               "max_value": 1277,
  -               "is_searchable": "true",
  -               "is_aggregatable": "true"
  +            "project": {
  +               "max_doc": 1,
  +               "doc_count": 1,
  +               "density": 100,
  +               "sum_doc_freq": 1,
  +               "sum_total_term_freq": 1,
  +               "searchable": true,
  +               "aggregatable": false,
  +               "min_value": "elasticsearch",
  +               "max_value": "elasticsearch"
  +            },
  +            "message": {
  +               "max_doc": 1,
  +               "doc_count": 1,
  +               "density": 100,
  +               "sum_doc_freq": 4,
  +               "sum_total_term_freq": 4,
  +               "searchable": true,
  +               "aggregatable": false,
  +               "min_value": "for",
  +               "max_value": "you"
  +            },
  +            "user": {
  +               "max_doc": 2,
  +               "doc_count": 2,
  +               "density": 100,
  +               "sum_doc_freq": 2,
  +               "sum_total_term_freq": 2,
  +               "searchable": true,
  +               "aggregatable": false,
  +               "min_value": "kimchy",
  +               "max_value": "kimchy"
               }
            }
         }
  +   },
  +   "conflicts": {
  +      "rating": "Field [rating] of type [whole-number] conflicts with existing field of type [text] in other index." <2>
      }
   }
   --------------------------------------------------
  +// TESTRESPONSE
   
   <1> The `_all` key indicates that it contains the field stats of all indices in the cluster.
   
  -NOTE: When using the cluster level field statistics it is possible to have conflicts if the same field is used in
  +<2> When using the cluster level field statistics it is possible to have conflicts if the same field is used in
   different indices with incompatible types. For instance a field of type `long` is not compatible with a field of
   type `float` or `string`. A section named `conflicts` is added to the response if one or more conflicts are raised.
   It contains all the fields with conflicts and the reason of the incompatibility.
   
  +[float]
  +==== Indices level field statistics example
  +
  +Request:
  +
  +[source,js]
  +--------------------------------------------------
  +GET /_field_stats?fields=rating,user,project,message&level=indices
  +--------------------------------------------------
  +// CONSOLE
  +
  +Response:
  +
   [source,js]
   --------------------------------------------------
   {
      "_shards": {
  -      "total": 1,
  -      "successful": 1,
  +      "total": 10,
  +      "successful": 10,
         "failed": 0
      },
      "indices": {
  -      "_all": {
  +      "github": {
            "fields": {
  -            "creation_date": {
  -               "max_doc": 1326564,
  -               "doc_count": 564633,
  -               "density": 42,
  -               "sum_doc_freq": 2258532,
  -               "sum_total_term_freq": -1,
  -               "min_value": "2008-08-01T16:37:51.513Z",
  -               "max_value": "2013-06-02T03:23:11.593Z",
  -               "is_searchable": "true",
  -               "is_aggregatable": "true"
  +            "rating": {
  +               "max_doc": 1,
  +               "doc_count": 1,
  +               "density": 100,
  +               "sum_doc_freq": 2,
  +               "sum_total_term_freq": 2,
  +               "searchable": true,
  +               "aggregatable": false,
  +               "min_value": "great",
  +               "max_value": "project"
  +            },
  +            "project": {
  +               "max_doc": 1,
  +               "doc_count": 1,
  +               "density": 100,
  +               "sum_doc_freq": 1,
  +               "sum_total_term_freq": 1,
  +               "searchable": true,
  +               "aggregatable": false,
  +               "min_value": "elasticsearch",
  +               "max_value": "elasticsearch"
  +            },
  +            "user": {
  +               "max_doc": 1,
  +               "doc_count": 1,
  +               "density": 100,
  +               "sum_doc_freq": 1,
  +               "sum_total_term_freq": 1,
  +               "searchable": true,
  +               "aggregatable": false,
  +               "min_value": "kimchy",
  +               "max_value": "kimchy"
               }
            }
  -      }
  -   },
  -   "conflicts": {
  -        "field_name_in_conflict1": "reason1",
  -        "field_name_in_conflict2": "reason2"
  -   }
  -}
  ---------------------------------------------------
  -
  -[float]
  -==== Indices level field statistics example
  -
  -Request:
  -
  -[source,js]
  ---------------------------------------------------
  -curl -XGET "http://localhost:9200/_field_stats?fields=rating,answer_count,creation_date,display_name&level=indices"
  ---------------------------------------------------
  -
  -Response:
  -
  -[source,js]
  ---------------------------------------------------
  -{
  -   "_shards": {
  -      "total": 1,
  -      "successful": 1,
  -      "failed": 0
  -   },
  -   "indices": {
  -      "stack": { <1>
  +      },
  +      "twitter": {
            "fields": {
  -            "creation_date": {
  -               "max_doc": 1326564,
  -               "doc_count": 564633,
  -               "density": 42,
  -               "sum_doc_freq": 2258532,
  -               "sum_total_term_freq": -1,
  -               "min_value": "2008-08-01T16:37:51.513Z",
  -               "max_value": "2013-06-02T03:23:11.593Z",
  -               "is_searchable": "true",
  -               "is_aggregatable": "true"
  -            },
  -            "display_name": {
  -               "max_doc": 1326564,
  -               "doc_count": 126741,
  -               "density": 9,
  -               "sum_doc_freq": 166535,
  -               "sum_total_term_freq": 166616,
  -               "min_value": "0",
  -               "max_value": "정혜선",
  -               "is_searchable": "true",
  -               "is_aggregatable": "false"
  -            },
  -            "answer_count": {
  -               "max_doc": 1326564,
  -               "doc_count": 139885,
  -               "density": 10,
  -               "sum_doc_freq": 559540,
  -               "sum_total_term_freq": -1,
  -               "min_value": 0,
  -               "max_value": 160,
  -               "is_searchable": "true",
  -               "is_aggregatable": "true"
  -            },
               "rating": {
  -               "max_doc": 1326564,
  -               "doc_count": 437892,
  -               "density": 33,
  -               "sum_doc_freq": 1751568,
  -               "sum_total_term_freq": -1,
  -               "min_value": -14,
  -               "max_value": 1277,
  -               "is_searchable": "true",
  -               "is_aggregatable": "true"
  +               "max_doc": 1,
  +               "doc_count": 1,
  +               "density": 100,
  +               "sum_doc_freq": -1,
  +               "sum_total_term_freq": 1,
  +               "searchable": true,
  +               "aggregatable": true,
  +               "min_value": 10,
  +               "min_value_as_string": "10",
  +               "max_value": 10,
  +               "max_value_as_string": "10"
  +            },
  +            "message": {
  +               "max_doc": 1,
  +               "doc_count": 1,
  +               "density": 100,
  +               "sum_doc_freq": 4,
  +               "sum_total_term_freq": 4,
  +               "searchable": true,
  +               "aggregatable": false,
  +               "min_value": "for",
  +               "max_value": "you"
  +            },
  +            "user": {
  +               "max_doc": 1,
  +               "doc_count": 1,
  +               "density": 100,
  +               "sum_doc_freq": 1,
  +               "sum_total_term_freq": 1,
  +               "searchable": true,
  +               "aggregatable": false,
  +               "min_value": "kimchy",
  +               "max_value": "kimchy"
               }
            }
         }
      }
   }
   --------------------------------------------------
  -
  +// TESTRESPONSE
   <1> The `stack` key means it contains all field stats for the `stack` index.
   
   [float]
  
positive.code:          }
        }
     }
  }'
  --------------------------------------------------
  
  <1> The fields to compute and return field stats for.
  <2> The set index constraints. Note that index constrains can be defined for fields that aren't defined in the `fields` option.
  
negative.code:          }
        }
     }
  }
  --------------------------------------------------
  // CONSOLE
  <1> Custom date format
  