Snippet of GWT client code attempting to "wrap" a number of ValidatableInputCell invoking onBrowserEvent for each

CompositeValidatableColumn

public class CompositeValidatableColumn<T> extends IdentityColumn<T> {

    public CompositeValidatableColumn(WrapperCell<T> cell) {
        super(cell);
    }

    @Override
    public WrapperCell<T> getCell() {
        return (WrapperCell<T>) super.getCell();
    }

    @Override
    public void onBrowserEvent(Context context, Element elem, final T object, NativeEvent event) {
        final int index = context.getIndex();
        final WrapperCell<T> wrapper = getCell();

        for (final HasCell<T, String> hasCell: wrapper.getInnerCells()) {
            final FieldUpdater<T, String> f = hasCell.getFieldUpdater();
            final Cell<String> innerCell = hasCell.getCell();
            if (innerCell instanceof ValidatableInputCell) {
                final ValidatableInputCell vic = (ValidatableInputCell) hasCell.getCell();

                final ValueUpdater<String> valueUpdater = f == null ? null : new ValueUpdater<String>() {
                    @Override
                    public void update(String value) {
                        f.update(index, object, value);
                    }
                };
                vic.onBrowserEvent(context, elem, vic.getViewData(object).getValue(), event, valueUpdater);
            }
        }

    }
}