code: protected boolean addItem(final Suggestion suggestion) {
          SelectionEvent.fire(MaterialAutoComplete.this, suggestion);
          if (getLimit() > 0) {
              if (suggestionMap.size() >= getLimit()) {
                  return false;
              }
          }
  
          if (suggestionMap.containsKey(suggestion)) {
              return false;
          }
  
          final ListItem displayItem = new ListItem();
          displayItem.setStyleName(AddinsCssName.MULTIVALUESUGGESTBOX_TOKEN);
  
          if (getType() == AutocompleteType.TEXT) {
              suggestionMap.clear();
              itemBox.setText(suggestion.getReplacementString());
          } else {
              final MaterialChip chip = chipProvider.getChip(suggestion);
              if (chip == null) {
                  return false;
              }
  
              registerHandler(chip.addClickHandler(event -> {
                  if (chipProvider.isChipSelectable(suggestion)) {
                      if (itemsHighlighted.contains(displayItem)) {
                          chip.removeStyleName(selectedChipStyle);
                          itemsHighlighted.remove(displayItem);
                      } else {
                          chip.addStyleName(selectedChipStyle);
                          itemsHighlighted.add(displayItem);
                      }
                  }
              }));
  
              if (chip.getIcon() != null) {
                  registerHandler(chip.getIcon().addClickHandler(event -> {
                      if (chipProvider.isChipRemovable(suggestion)) {
                          suggestionMap.remove(suggestion);
                          list.remove(displayItem);
                          itemsHighlighted.remove(displayItem);
                          ValueChangeEvent.fire(MaterialAutoComplete.this, getValue());
                          suggestBox.showSuggestionList();
                      }
                  }));
              }
  
              suggestionMap.put(suggestion, chip);
              displayItem.add(chip);
              list.insert(displayItem, list.getWidgetCount() - 1);
          }
          return true;
      }
docs: Adding the item value using Material Chips added on auto complete box