Vaadin 8 Binding Custom Business Object to CheckBoxGroup

Hello Everyone,

I'm upgrading one of my Vaadin projects to version 8 and I'm facing a problem when binding a custom Business Object to a CheckBoxGroup. I simplified my project into the following test scenario:

Class Person:

package com.vaadin.test;

import java.util.Date;
import java.util.Set;

public class Person {

    private String name;
    private Set<Tag> tags;

    public Person(String name) {
        super();
        this.name = name;
    }

    public String getName() {
        return this.name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Set<Tag> getTags() {
        return tags;
    }

    public void setTags(Set<Tag> tags) {
        this.tags = tags;
    }
}

An object of the class "Person" can have many Tags. The class Tag looks like this:

package com.vaadin.test;

public class Tag {

    private String name;

    public Tag(String name) {
        super();
        this.name = name;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return name;
    }
}

I created a simple UI with a TextField, a CheckBoxGroup and a Binder:

package com.vaadin.test;

import java.util.HashSet;
import com.vaadin.annotations.Theme;
import com.vaadin.data.Binder;
import com.vaadin.server.VaadinRequest;
import com.vaadin.ui.CheckBoxGroup;
import com.vaadin.ui.Label;
import com.vaadin.ui.TextField;
import com.vaadin.ui.UI;
import com.vaadin.ui.VerticalLayout;

@Theme("valo")
public class TestUI extends UI {

    private static final long serialVersionUID = 1L;

    @Override
    protected void init(VaadinRequest request) {
        Person person = new Person("Marcus");
        person.setTags(new HashSet<Tag>() {{ add(new Tag("Foo")); add(new Tag("Bar")); }});

        Binder<Person> binder = new Binder<>(Person.class);

        TextField name = new TextField();
        binder.bind(name, Person::getName, Person::setName);    

        CheckBoxGroup<Tag> tags = new CheckBoxGroup<>();
        tags.setItems(new HashSet<Tag>() {{ add(new Tag("Foo")); add(new Tag("Bar")); add(new Tag("Test")); }});
        binder.bind(tags, Person::getTags, Person::setTags);

        this.setContent(new VerticalLayout(new Label("Hello Vaadin!"), name, tags));      

        binder.setBean(person);
    }
}

The expected behavior for me would be, that the CheckBoxes Foo and Bar are preselected, when the UI is rendered:

But the actual result is that none of the CheckBoxes are preselected:

When I debug my code I can see that updateSelection of Class AbstractMultiSelect is called with [Bar, Foo] as addedItems, but unfortunatly this update is not populated to the UI.

I think I'm missing something here, but I'm note sure what it could be. Do I need to implement a custom Converter or some kind of Comparator to tell Vaadin that new Tag("Foo") is equal to new Tag("Foo")? 

Thanks in advance.