Grid footer doesn't work inside Grid details generator

Dear Vaadin Devs / users

I am new to Vaadin and really love the way things work. There is one issue that is just driving me nuts. Perhaps it is a bug otherwise please let me know what am doing wrong. 

If I declare a grid footer it is added fine. However, if I define a grid within the scope of details generator of another grid the footer stops functioning. I see an empty row as a footer but nothing inside. 

Is there a special magic to the grid footer when applied to a grid inside another grids details generator

final VerticalLayout layout = new VerticalLayout();

        Grid grid = new Grid();
        grid.addColumn("name");
        grid.addColumn("address");

        grid.addRow("John", "Melbourne");
        grid.addRow("David", "Sydney");
        grid.addRow("Alex", "Singapore");

        FooterRow footer = grid.prependFooterRow();
        footer.getCell("name").setText("NameFooter");
        footer.getCell("address").setText("AddressFooter");

        grid.setDetailsGenerator(rowReference -> {

            Grid gridInternal = new Grid();

            gridInternal.addColumn("name");
            gridInternal.addColumn("address");

            gridInternal.addRow("Sally", "Adelaide");
            gridInternal.addRow("Noks", "Perth");

            FooterRow footerInternal = gridInternal.prependFooterRow();
            footerInternal.getCell("name").setText("NameFooter");
            footerInternal.getCell("address").setText("AddressFooter");


            // Wrap up all the parts into a vertical layout
            VerticalLayout layoutInternal = new VerticalLayout(gridInternal);
            layoutInternal.setSpacing(true);
            layoutInternal.setMargin(true);
            return layoutInternal;

        });

        grid.addItemClickListener(event -> {
            if (event.isDoubleClick()) {
                Object itemId = event.getItemId();
                grid.setDetailsVisible(itemId, !grid.isDetailsVisible(itemId));
            }

        });
        layout.addComponents(grid);
        layout.setMargin(true);
        layout.setSpacing(true);

        setContent(layout);

See attached (the footer is not present even if you scroll down)