@Override
    public List<Map<String, String>> taskConfigs(int maxTasks) {
        ArrayList<Map<String, String>> configs = new ArrayList<>();
        // Only one input stream makes sense.
        configs.add(props);
        return configs;
    }
Very simple source connector that works with stdin or a file.
connect/file/src/main/java/org/apache/kafka/connect/file/FileStreamSourceConnector.java