class JsonRpc2_0Web3j implements Web3j {

    @Override
    public void shutdown() {
        scheduledExecutorService.shutdown();
        try {
            web3jService.close();
        } catch (IOException e) {
            throw new RuntimeException("Failed to close web3j service", e);
        }
    }

    public  JsonRpc2_0Web3j(Web3jService web3jService);
    public  JsonRpc2_0Web3j(
            Web3jService web3jService, long pollingInterval,
            ScheduledExecutorService scheduledExecutorService);

}