if (seller != null && car != null){
                    Offer offer = this.modelMapper.map(offerDto,Offer.class);
                    offer.setAddedOn(date);
                    offer.setCar(car);
                    offer.setSeller(seller);
                    this.offerRepository.saveAndFlush(offer);

                    String stringData = dateTime.format(DateTimeFormatter.ofPattern("dd/MM/yyyy HH:mm"));
                    sb.append(String.format("Successfully imported offer - %s",
                            picture.getName())).append(System.lineSeparator()));
                }else {
                    sb.append(String.format(INVALID_MASSAGE,"offer")).append(System.lineSeparator());
                }