Table editing mode with BeanItemContainer and BeanContainer works incorrectly

Originally by damian.czernous@gmail.com

1. Bean(Item)Container expects JavaBeans that are mutable by definition.
2. Table to bind JavaBean fields with rows uses hashed collections (HashMap) that prefers immutable objects.

When JavaBean overrides hashcode (& equals) method (e.g. to compare by value) Table can't properly refresh rows after finished editing. During Table.setEditable( false ) execution changed rows disappears.

Editing works fine for JavaBeans that don't override hashcode method.

public class JavaBean
{
  // fields with getters & setters

  @Override
  public int hashCode()
  {
    ...
  }
}

public class SomeUI extends UI
{
  private Table table;
  private Button edit;

  @Override
  protected void init( VaadinRequest vaadinRequest )
  {
    BeanItemContainer container = new BeanItemContaner( JavaBean.class );
    container.addBean( new JavaBean() );

    table = new Table( null, container );

    edit = new Button( "edit", new TurnOnOffEditingAction( table ) );

    // set content
  }
}

public class TurnOnOffEditingAction implements Button.ClickListener
{
    private final Table table;
    
    // constructor

    @Override
    public void buttonClick( Button.ClickEvent event )
    {
        if( table.isEditable() )
        {
            event.getButton().setCaption( "edit" );
            table.setEditable( false );
        }
        else
        {
            event.getButton().setCaption( "save" );
            table.setEditable( true );
        }
    }
}

Imported from https://dev.vaadin.com/ issue #13403

Start by reproducing the sample with BeanItemContainer, a JavaBean that overrides equals and hashCode, and a Table whose editing mode is toggled. Trace the Table editing and row-refresh path, then verify that edited rows remain present after setEditable(false) and that existing behavior still works for beans without hashCode overrides.