anchor.diff:  `ignore_unmapped`::
   
       Indicates if the unmapped field should be treated as a missing value. Setting it to `true` is equivalent to specifying
  -    an `unmapped_type` in the field sort. The default is `false` (unmapped field are causing the search to fail).
  +    an `unmapped_type` in the field sort. The default is `false` (unmapped field cause the search to fail).
   
   NOTE: geo distance sorting does not support configurable missing values: the
   distance will always be considered equal to +Infinity+ when a document does not
  
positive.code: [[search-request-sort]]
  === Sort
  
  Allows to add one or more sort on specific fields. Each sort can be
  reversed as well. The sort is defined on a per field level, with special
  field name for `_score` to sort by score, and `_doc` to sort by index order.
  
  
negative.code: ==== Ignoring Unmapped Fields
  
  By default, the search request will fail if there is no mapping
  associated with a field. The `unmapped_type` option allows you to ignore
  fields that have no mapping and not sort by them. The value of this
  parameter is used to determine what sort values to emit. Here is an
  example of how it can be used:
  