anchor.diff:  <2> Any arbitrary data can be passed to the `session_data` field as it will be entirely ignored.
   <3> The `session_data` will also ignore values that are not JSON objects.
   
  -The entire mapping type may be disabled as well, in which case the document is
  +The entire mapping may be disabled as well, in which case the document is
   stored in the <<mapping-source-field,`_source`>> field, which means it can be
   retrieved, but none of its contents are indexed in any way:
   
  
positive.code: GET my_index/_mapping <3>
  --------------------------------------------------
  // CONSOLE
  <1> The entire mapping type is disabled.
  <2> The document can be retrieved.
  <3> Checking the mapping reveals that no fields have been added.
  
  TIP: The `enabled` setting can be updated on existing fields
  using the <<indices-put-mapping,PUT mapping API>>.
  
  
negative.code:         "type": "date"
        },
        "session_data": { <1>
          "type": "object",
          "enabled": false
        }
      }
  