@Override
    public EthSendTransaction sendTransaction(
            BigInteger gasPrice,
            BigInteger gasLimit,
            String to,
            String data,
            BigInteger value,
            boolean constructor)
            throws IOException {
        throw new UnsupportedOperationException(
                "Only read operations are supported by this transaction manager");
    }
@Test
    public void testSendTransaction() {
        ReadonlyTransactionManager readonlyTransactionManager =
                new ReadonlyTransactionManager(web3j, "");
        assertThrows(
                UnsupportedOperationException.class,
                () ->
                        readonlyTransactionManager.sendTransaction(
                                BigInteger.ZERO, BigInteger.ZERO, "", "", BigInteger.ZERO));
    }