/**
   * Returns empty table widget with attributes
   *
   * @return table widget
   */
  public CellTable<Attribute> getEmptyTable() {

    // Table data provider.
    dataProvider = new ListDataProvider<Attribute>(list);

    // Cell table
    table = new PerunTable<Attribute>(list);
    table.removeRowCountChangeHandler(); // remove row count change handler

    // Connect the table to the data provider.
    dataProvider.addDataDisplay(table);

    // Sorting
    ListHandler<Attribute> columnSortHandler = new ListHandler<Attribute>(dataProvider.getList());
    table.addColumnSortHandler(columnSortHandler);

    // table selection
    table.setSelectionModel(
        selectionModel, DefaultSelectionEventManager.<Attribute>createCheckboxManager());

    // set empty content & loader
    table.setEmptyTableWidget(loaderImage);

    // because of tab index
    table.setKeyboardSelectionPolicy(KeyboardSelectionPolicy.DISABLED);

    // checkbox column
    if (checkable) {

      // checkbox column column
      Column<Attribute, Attribute> checkBoxColumn =
          new Column<Attribute, Attribute>(new PerunCheckboxCell<Attribute>(true, false, false)) {
            @Override
            public Attribute getValue(Attribute object) {
              // Get the value from the selection model.
              GeneralObject go = object.cast();
              go.setChecked(selectionModel.isSelected(object));
              return go.cast();
            }
          };

      // updates the columns size
      table.setColumnWidth(checkBoxColumn, 40.0, Unit.PX);

      // Add the columns

      // Checkbox column header
      CheckboxCell cb = new CheckboxCell();
      Header<Boolean> checkBoxHeader =
          new Header<Boolean>(cb) {
            public Boolean getValue() {
              return false; // return true to see a checked checkbox.
            }
          };
      checkBoxHeader.setUpdater(
          new ValueUpdater<Boolean>() {
            public void update(Boolean value) {
              // sets selected to all, if value = true, unselect otherwise
              for (Attribute obj : list) {
                if (obj.isWritable()) {
                  selectionModel.setSelected(obj, value);
                }
              }
            }
          });

      table.addColumn(checkBoxColumn, checkBoxHeader);
    }

    // Create ID column.
    table.addIdColumn("Attr ID", null, 90);

    // Name column
    Column<Attribute, Attribute> nameColumn = JsonUtils.addColumn(new PerunAttributeNameCell());

    // Value column
    Column<Attribute, Attribute> valueColumn = JsonUtils.addColumn(new PerunAttributeValueCell());
    valueColumn.setFieldUpdater(
        new FieldUpdater<Attribute, Attribute>() {
          public void update(int index, Attribute object, Attribute value) {
            object = value;
            selectionModel.setSelected(object, object.isAttributeValid());
          }
        });

    // Description column
    Column<Attribute, Attribute> descriptionColumn =
        JsonUtils.addColumn(new PerunAttributeDescriptionCell());

    // Sorting name column
    nameColumn.setSortable(true);
    columnSortHandler.setComparator(
        nameColumn, new AttributeComparator<Attribute>(AttributeComparator.Column.TRANSLATED_NAME));

    // Sorting description column
    descriptionColumn.setSortable(true);
    columnSortHandler.setComparator(
        descriptionColumn,
        new AttributeComparator<Attribute>(AttributeComparator.Column.TRANSLATED_DESCRIPTION));

    // Add sorting
    this.table.addColumnSortHandler(columnSortHandler);

    // updates the columns size
    this.table.setColumnWidth(nameColumn, 200.0, Unit.PX);

    // Add the columns.
    this.table.addColumn(nameColumn, "Name");
    this.table.addColumn(valueColumn, "Value");
    this.table.addColumn(descriptionColumn, "Description");

    return this.table;
  }
  public Widget draw() {

    // contentWidget.setSize("100%", "100%");

    DockLayoutPanel ft = new DockLayoutPanel(Style.Unit.PX);
    contentWidget.setWidget(ft);

    final DataGrid gridTable = new DataGrid();
    gridTable.setSize("100%", "100%");

    final ArrayList<Attribute> vosList = new ArrayList<Attribute>();
    final GetAttributesV2 getVos =
        new GetAttributesV2(
            new JsonCallbackEvents() {
              public void onFinished(JavaScriptObject jso) {
                vosList.addAll(
                    new TableSorter<Attribute>()
                        .sortByAttrNameTranslation(JsonUtils.<Attribute>jsoAsList(jso)));
                gridTable.setRowData(vosList);
                gridTable.redraw();
              }
            });
    getVos.getUserAttributes(3411);
    getVos.retrieveData();

    gridTable.setSelectionModel(
        new MultiSelectionModel<Attribute>(new GeneralKeyProvider<Attribute>()));
    final SelectionModel<Attribute> selectionModel = gridTable.getSelectionModel();
    gridTable.setKeyboardSelectionPolicy(
        HasKeyboardSelectionPolicy.KeyboardSelectionPolicy.DISABLED);

    Column<Attribute, Boolean> checkBoxColumn =
        new Column<Attribute, Boolean>(new CheckboxCell(true, true)) {
          @Override
          public Boolean getValue(Attribute object) {
            // Get the value from the selection model.
            return selectionModel.isSelected(object);
          }
        };
    checkBoxColumn.setFieldUpdater(
        new FieldUpdater<Attribute, Boolean>() {
          @Override
          public void update(int i, Attribute Attribute, Boolean aBoolean) {
            selectionModel.setSelected(Attribute, aBoolean);
          }
        });

    // Checkbox column header
    CheckboxCell cb = new CheckboxCell();
    Header<Boolean> checkBoxHeader =
        new Header<Boolean>(cb) {
          public Boolean getValue() {
            return false; // return true to see a checked checkbox.
          }
        };
    checkBoxHeader.setUpdater(
        new ValueUpdater<Boolean>() {
          public void update(Boolean value) {
            // sets selected to all, if value = true, unselect otherwise
            for (Attribute obj : vosList) {
              selectionModel.setSelected(obj, value);
            }
          }
        });

    gridTable.addColumn(checkBoxColumn, checkBoxHeader, checkBoxHeader);
    gridTable.setColumnWidth(checkBoxColumn, 40.0, Style.Unit.PX);

    TextColumn<Attribute> idColumn =
        new TextColumn<Attribute>() {
          @Override
          public String getValue(Attribute object) {
            return String.valueOf(object.getId());
          }
        };

    if (JsonUtils.isExtendedInfoVisible()) {
      gridTable.addColumn(idColumn, "Id", "Id");
      gridTable.setColumnWidth(idColumn, "90px");
    }

    // Name column
    Column<Attribute, Attribute> nameColumn = JsonUtils.addColumn(new PerunAttributeNameCell());

    // Description column
    Column<Attribute, Attribute> descriptionColumn =
        JsonUtils.addColumn(new PerunAttributeDescriptionCell());

    // Value column
    Column<Attribute, Attribute> valueColumn =
        JsonUtils.addColumn(
            new PerunAttributeValueCell(),
            new FieldUpdater<Attribute, Attribute>() {
              public void update(int index, Attribute object, Attribute value) {
                object = value;
                selectionModel.setSelected(object, object.isAttributeValid());
              }
            });

    ColumnSortEvent.ListHandler<Attribute> columnSortHandler =
        new ColumnSortEvent.ListHandler<Attribute>(vosList);
    gridTable.addColumnSortHandler(columnSortHandler);

    // Sorting name column
    nameColumn.setSortable(true);
    columnSortHandler.setComparator(
        nameColumn, new AttributeComparator<Attribute>(AttributeComparator.Column.TRANSLATED_NAME));

    // Sorting description column
    descriptionColumn.setSortable(true);
    columnSortHandler.setComparator(
        descriptionColumn,
        new AttributeComparator<Attribute>(AttributeComparator.Column.TRANSLATED_DESCRIPTION));

    // Add sorting
    gridTable.addColumnSortHandler(columnSortHandler);

    // updates the columns size
    gridTable.setColumnWidth(nameColumn, 200.0, Style.Unit.PX);
    gridTable.setColumnWidth(valueColumn, 420.0, Style.Unit.PX);

    gridTable.addColumn(nameColumn, "Name");
    gridTable.addColumn(valueColumn, "Value");
    gridTable.addColumn(descriptionColumn, "Description");

    TabMenu tabMenu = new TabMenu();

    tabMenu.addWidget(
        TabMenu.getPredefinedButton(
            ButtonType.ADD,
            "",
            new ClickHandler() {
              @Override
              public void onClick(ClickEvent clickEvent) {
                session.getTabManager().addTabToCurrentTab(new TestDataGridTabItem(), true);
              }
            }));

    ft.addNorth(tabMenu, 50);
    ft.add(gridTable);

    return getWidget();
  }