@Override
  public void cleanUp() {
    CachedSubscriptionPollResponse response;
    while (Objects.nonNull(response = poll())) {
      response.closeMemoryBlock();
      SubscriptionPollResponseCache.getInstance().invalidate(response);
    }

    hasNoMore = false;
  }
The {@code SubscriptionEventExtendableResponse} class represents a subscription event response
that can dynamically change as new responses are fetched. It maintains a list of {@link
CachedSubscriptionPollResponse} objects and provides methods for managing and serializing these
responses.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/subscription/event/response/SubscriptionEventExtendableResponse.java