Print Grid with iText

Flow
1

Hallo,

I change my Vaadin 7.7.17 App to Vaadin 13.0.8.
I fill my Grid with Spring jpa.
In Vaadin 7, I get the visible rows (with filters) over grid.getContainerDataSource().

for (Object visibleItemId : table.getContainerDataSource().getItemIds()) {
      Item item = table.getContainerDataSource().getItem(visibleItemId);
      for (Object columnId : visibleColumns) {
        String[] feldTempColums = columnId.toString().split(":");
        String spalte = feldTempColums[1]
.replaceAll("\\]", "");

        Property itemProperty = item.getItemProperty(spalte);
        Object value = itemProperty.getValue();
        String stringValue = "";
        if (value != null) {
          if (itemProperty.getType().equals(Date.class)) {
            LOG.debug("date: " + value);
            Date date = (Date) value;
            SimpleDateFormat simpleDateFormat = new SimpleDateFormat("dd.MM.yyyy");
            value = simpleDateFormat.format(date);
            LOG.debug("date: " + value);
          } else if (itemProperty.getType().equals(BigDecimal.class)) {
            value = NumberFormat.getCurrencyInstance(Locale.GERMANY).format(value);
          }
          stringValue = convertBooleanOutput(value.toString());
        }
        PdfPCell cell = new PdfPCell(new Phrase(stringValue, font));
        pdfPTable.addCell(cell);
      }
    }

How can I do this, with Vaadin 13 and the new Grid?
Thanks
Patrick