### Question:
Utils { public static String transactionIdToString(TransactionId transactionId) { String txId = "0.0." + transactionId.accountId.account + "-" + transactionId.validStart.getEpochSecond() + "-" + transactionId.validStart.getNano(); return txId; }  static String timestampToDate(long seconds, int nanos); static String timestampToTime(long seconds, int nanos); static String applicationMessageIdToString(ApplicationMessageID transactionId); static String transactionIdToString(TransactionId transactionId); static Credit creditFromCreditBPM(CreditBPM creditBPM, String threadId); static CreditBPM creditBPMFromCredit(Credit credit); static Settlement settlementFromSettleProposeBPM(SettleProposeBPM settleProposeBPM, String threadId); static ApplicationMessageID applicationMessageIdFromString(String appMessageId); static String getThreadId(); static Money moneyFromSettlement(Settlement settlement); static ResponseEntity<SettlementRest> serverError();  }### Answer:
@Test public void testTransactionIdToString() { Instant timeNow = Instant.now(); String txCompare = "0.0.2-".concat(Long.toString(timeNow.getEpochSecond())).concat("-").concat(Integer.toString(timeNow.getNano())); TransactionId transactionId = TransactionId.withValidStart(AccountId.fromString("0.0.2"), timeNow); String txString = Utils.transactionIdToString(transactionId); assertEquals(txCompare, txString); }