Implementing a CRUD using an editable Grid component

In this section, we'll implement a component containing an editable Grid. The following is a screenshot of the application showing the Grid component in edit mode:

For simplicity, in this example, we'll omit the add and the delete CRUD operations for now. Let's start by creating a class to encapsulate the component as follows:

public class EditableGridCrud extends Composite {

    private Grid<User> grid = new Grid<>();

    public EditableGridCrud() {
        initLayout();
        initBehavior();
    }

    private void initLayout() {
        grid.setSizeFull();
        VerticalLayout layout = new VerticalLayout(grid);

        setCompositionRoot(layout);
        setSizeFull();
    }

    private void initBehavior() {
    }
}

The class, which extends Composite, declares a Grid to show User instances. There are several...