@Override
    public Collection<Entry<?, ?>> process(IncomingMessageEnvelope message, KeyValueStore store) {
      return ImmutableSet.of(new Entry<>(message.getKey(), message.getMessage()));
    }
Helper function to recursively delete all files from local blob store
@param dirIndex
samza-test/src/test/java/org/apache/samza/storage/kv/BlobStoreStateBackendIntegrationTest.java