Vaadin: Refresh Grid-Rows when underlying Object updated

TestUI.java

import com.vaadin.server.VaadinRequest;
import com.vaadin.spring.annotation.SpringUI;
import com.vaadin.ui.Grid;
import com.vaadin.ui.TextField;
import com.vaadin.ui.UI;
import com.vaadin.ui.themes.ValoTheme;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.RequiredArgsConstructor;

import java.util.Arrays;
import java.util.List;

@SpringUI(path = "/test")
public class TestUI extends UI {

    private ArticleGroup articleGroup = new ArticleGroup(Arrays.asList(
            new Article("One", 10, 0),
            new Article("Two", 20, 0),
            new Article("Three", 5, 0)));

    private Grid<Article> grid;

    private Grid.Column quantityColumn;

    @Override
    protected void init(VaadinRequest request) {
        articleGroup.updateDistributions();


        grid = new Grid<>("Distribution Grid");
        grid.setSizeFull();
        grid.addFooterRowAt(0);

        grid.addColumn(Article::getName)
                .setCaption("Name");

        quantityColumn = grid.addComponentColumn(article -> {
            TextField quantity = new TextField();
            quantity.setValue(String.valueOf(article.getQuantity()));
            quantity.setWidth("100%");
            quantity.addStyleName(ValoTheme.TEXTAREA_ALIGN_RIGHT);
            quantity.addStyleName(ValoTheme.TEXTFIELD_BORDERLESS);
            quantity.addValueChangeListener(e -> quantityChanged(article, Integer.parseInt(e.getValue())));
            return quantity;
        })
                .setCaption("Quantity");

        grid.addColumn(Article::getDistribution)
                .setCaption("Distribution");


        grid.setItems(articleGroup.getArticles());
        setContent(grid);

    }

    private void quantityChanged(Article article, Integer newValue) {
        article.setQuantity(newValue);
        articleGroup.updateDistributions();

        grid.getFooterRow(0)
                .getCell(quantityColumn)
                .setText(String.valueOf(articleGroup.getSum()));
        grid.getDataProvider().refreshAll();
    }


    @RequiredArgsConstructor
    @Data
    public static class ArticleGroup {
        private final List<Article> articles;

        public void updateDistributions() {
            articles.stream()
                    .forEach(a -> a.setDistribution(a.getQuantity() / (double) getSum()));
        }

        public int getSum() {
            return articles.stream()
                    .mapToInt(Article::getQuantity)
                    .sum();
        }
    }

    @AllArgsConstructor
    @NoArgsConstructor
    @Data
    public static class Article {
        private String name;

        private int quantity;

        private double distribution;
    }
}