Выдает ошибку java.lang.NullPointerException: null

Вот код метода:

 @Override
    public void accountImport(String fileName, AccountDto accountDto) {
        try(FileWriter writer = new FileWriter(fileName, false))

        {
            Integer id = accountDto.getId();
            String stId= id.toString();

            Long number = accountDto.getNumber();
            String stNumber = number.toString();

            String date = accountDto.getDate();

            String beneficiary = accountDto.getBeneficiary();

            String comment = accountDto.getComment();

            Long amount = accountDto.getAmount();
            String stAmount = amount.toString();

            String currency = accountDto.getCurrency();

            String finall = stId+","+stNumber+","+date+","+beneficiary+","+comment+","+stAmount+","+currency;
            for (int i = 0; i < finall.length(); i++)
                writer.write(finall.charAt(i));

        } catch (IOException e) {
            throw  new ValidateException("ERROR");
        }

    }

Вот код контроллера:

@PostMapping("/import")
    public  ResponseEntity importAccount(@RequestParam(name = "fileName",required = false) String fileName, @RequestBody AccountDto accountDto){
        accountServiceImport.accountImport(fileName,accountDto);
        return  new ResponseEntity(HttpStatus.OK);
    }

Вот запрос в Postman:

{
    "fileName": "C:\\Users\\Admin\\Documents\\task\\text.csv",
  "account":{
    "id": 0,
    "number": 84822,
    "date": "2022-04-06  22:58 ",
    "beneficiary": "Bob",
    "comment": "For",
    "amount": 8482200,
    "currency": "USA"
    }
    
        
}