anchor.diff:  highlighting framework. For implementation details you can check
   `ScoreOrderFragmentsBuilder.java` class.
   
  -If the `number_of_fragments` value is set to 0 then no fragments are
  -produced, instead the whole content of the field is returned, and of
  -course it is highlighted. This can be very handy if short texts (like
  -document title or address) need to be highlighted but no fragmentation
  -is required. Note that `fragment_size` is ignored in this case.
  -
  -[source,js]
  ---------------------------------------------------
  -{
  -    "query" : {...},
  -    "highlight" : {
  -        "fields" : {
  -            "_all" : {},
  -            "bio.title" : {"number_of_fragments" : 0}
  -        }
  -    }
  -}
  ---------------------------------------------------
  -
  -When using `fast-vector-highlighter` one can use `fragment_offset`
  -parameter to control the margin to start highlighting from.
  -
   [[highlighting-settings]]
   ==== Global Settings
   
  
positive.code: in the mapping), it will be used, otherwise, the actual `_source` will
  be loaded and the relevant field will be extracted from it.
  
  If `term_vector` information is provided by setting `term_vector` to 
  `with_positions_offsets` in the mapping then the fast vector 
  highlighter will be used instead of the plain highlighter.  The fast vector highlighter:
  
  * Is faster especially for large fields (> `1MB`)
  * Can be customized with `boundary_chars`, `boundary_max_scan`, and 
   `fragment_offset` (see below)
  * Requires setting `term_vector` to `with_positions_offsets` which 
    increases the size of the index
  
  Here is an example of setting the `content` field to allow for
  
negative.code:     }
  }
  --------------------------------------------------
  
  If the `number_of_fragments` value is set to 0 then no fragments are
  produced, instead the whole content of the field is returned, and of
  course it is highlighted. This can be very handy if short texts (like
  document title or address) need to be highlighted but no fragmentation
  is required. Note that `fragment_size` is ignored in this case.
  
  [source,js]
  --------------------------------------------------
  {
      "query" : {...},
      "highlight" : {
          "fields" : {
              "_all" : {},
              "bio.title" : {"number_of_fragments" : 0}
          }
      }
  }
  --------------------------------------------------
  
  When using `fast-vector-highlighter` one can use `fragment_offset`
  parameter to control the margin to start highlighting from.
  
  ==== Highlight query
  
  It is also possible to highlight against a query other than the search
  query by setting `highlight_query`.  This is especially useful if you
  