@Override
    public void configure(WorkerConfig config) {
        super.configure(config);
        file = new File(config.getString(StandaloneConfig.OFFSET_STORAGE_FILE_FILENAME_CONFIG));
    }
Implementation of OffsetBackingStore that saves data locally to a file. To ensure this behaves
similarly to a real backing store, operations are executed asynchronously on a background thread.
connect/runtime/src/main/java/org/apache/kafka/connect/storage/FileOffsetBackingStore.java