### Question:
LedgersSpiPaymentMapper { public String mapToRemittanceString(RemittanceInformationStructuredTO remittanceInformationStructuredTO) { return Optional.ofNullable(remittanceInformationStructuredTO) .map(RemittanceInformationStructuredTO::getReference) .orElse(null); }  SpiSinglePayment toSpiSinglePayment(PaymentTO paymentTO); SpiPeriodicPayment mapToSpiPeriodicPayment(PaymentTO paymentTO); SpiBulkPayment mapToSpiBulkPayment(PaymentTO paymentTO); String mapToRemittanceString(RemittanceInformationStructuredTO remittanceInformationStructuredTO);  }### Answer:
@Test void mapToSpiRemittance() { RemittanceInformationStructuredTO remittanceInformationStructuredTO = jsonReader.getObjectFromFile("json/mappers/remittance.json", RemittanceInformationStructuredTO.class); String actual = ledgersSpiPaymentMapper.mapToRemittanceString(remittanceInformationStructuredTO); String expected = "Ref Number Merchant"; assertEquals(expected, actual); }