transactionBuilder.kt

 val txBuilder = ledgerService.createTransactionBuilder()
                    .setNotary(notary.name)
                    .setTimeWindowBetween(Instant.now(), Instant.now().plusMillis(Duration.ofDays(1).toMillis()))
                    .addOutputState(iouState)
                    .addInputState(inputStateRef)
                    .addCommand(IOUContract.Issue())
                    .addCommand(IOUContract.Transfer())
                    .addSignatories(iouState.participants)