code: @Override
      public void writeFragmentTo(MwsWriter w) {
          w.write("InvoiceRequirement", invoiceRequirement);
          w.write("BuyerSelectedInvoiceCategory", buyerSelectedInvoiceCategory);
          w.write("InvoiceTitle", invoiceTitle);
          w.write("InvoiceInformation", invoiceInformation);
      }
docs: Write members to a MwsWriter.
  
  @param w
  The writer to write to.