public static TransactionInput coinbaseInput(Transaction parentTransaction, byte[] scriptBytes) {
        Objects.requireNonNull(parentTransaction);
        checkArgument(scriptBytes.length >= 2 && scriptBytes.length <= 100, () ->
                "script must be between 2 and 100 bytes: " + scriptBytes.length);
        return new TransactionInput(parentTransaction, scriptBytes, TransactionOutPoint.UNCONNECTED);
    }
@Test
    public void coinbaseInput() {
        TransactionInput coinbaseInput = TransactionInput.coinbaseInput(new Transaction(), new byte[2]);
        assertTrue(coinbaseInput.isCoinBase());
    }