public Map<String, String> coreReportMessage() {
    final Map<String, String> result = new HashMap<>();
    result.put("brokerId", brokerId);
    result.put("topicName", topicName);
    result.put("size of inputPendingQueue", String.valueOf(inputPendingQueue.size()));
    result.put("size of prefetchingQueue", String.valueOf(prefetchingQueue.size()));
    result.put("size of inFlightEvents", String.valueOf(inFlightEvents.size()));
    result.put("commitIdGenerator", commitIdGenerator.toString());
    result.put("states", states.toString());
    result.put("isCompleted", String.valueOf(isCompleted));
    result.put("isClosed", String.valueOf(isClosed));
    return result;
  }
@return {@code true} if nack successfully
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/subscription/broker/SubscriptionPrefetchingQueue.java