anchor.diff:  ==== Ignoring Unmapped Fields
   
   By default, the search request will fail if there is no mapping
  -associated with a field. The `unmapped_type` option allows to ignore
  +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:
  
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: ==== Missing Values
  
  The `missing` parameter specifies how docs which are missing
  the sort field should be treated: The `missing` value can be
  set to `_last`, `_first`, or a custom value (that
  will be used for missing docs as the sort value).
  The default is `_last`.
  