anchor.diff:  
     StringSelectionOptions.withOptionGroups(List<OptionGroup<T>> optionGroups,
         {ItemRenderer<T> toFilterableString,
  -      StringSuggestionFilter suggestionFilter,
  +      StringSuggestionFilter<T> suggestionFilter,
         ItemRenderer sanitizeString: _stringFormatSuggestion,
         bool shouldSort: false})
         : _toFilterableString = toFilterableString ??
  
positive.code:   /// [shouldSort] is a simple way to apply the default sorting rules.
    StringSelectionOptions(List<T> options,
        {ItemRenderer<T> toFilterableString,
        StringSuggestionFilter suggestionFilter,
        ItemRenderer sanitizeString: _stringFormatSuggestion,
        bool shouldSort: false})
        : this.withOptionGroups([new OptionGroup(options)],
  
negative.code: String _stringFormatSuggestion<T>(T value) =>
      '$value'.replaceAll(' ', '').toLowerCase();
  
  typedef bool StringSuggestionFilter<T>(T suggestion, String filterQuery);
  
  /// The class is meant to be used in areas where a selection can be represented
  /// as a string.
  