code: function () {
              var indexes = this.getHighlight();
              var rightMostIndex = indexes[indexes.length - 1];
              var limit = this.insertedOptionsCount();
  
              var index = rightMostIndex + 1;
  
              if (index <= limit) {
                  this.highlightOption(index);
              } else {
                  this.removeHighlight();
                  this._enterInputField();
              }
          }
docs: Performs right navigation when the widget is in highlighted mode. What it means is that it highlights the
  next inserted option if there is one, otherwise it goes back to the text input field at its beginning.