@Override
    public void start(Map<String, String> props) {
        this.props = props;
        AbstractConfig config = new AbstractConfig(CONFIG_DEF, props);
        String filename = config.getString(FILE_CONFIG);
        filename = (filename == null || filename.isEmpty()) ? "standard output" : filename;
        log.info("Starting file sink connector writing to {}", filename);
    }
Very simple sink connector that works with stdout or a file.
connect/file/src/main/java/org/apache/kafka/connect/file/FileStreamSinkConnector.java