public boolean isTopicSubscribedByConsumerGroup(final String topic) {
    final Set<String> subscribedConsumerIdSet = topicNameToSubscribedConsumerIdSet.get(topic);
    if (Objects.isNull(subscribedConsumerIdSet)) {
      return false;
    }
    return !subscribedConsumerIdSet.isEmpty();
  }
Get the consumers subscribing the given topic in this group.

@param topic The topic name.
@return The set of consumer IDs subscribing the given topic in this group. If no consumer is
    subscribing the topic, return an empty set.
iotdb-core/node-commons/src/main/java/org/apache/iotdb/commons/subscription/meta/consumer/ConsumerGroupMeta.java