@Override
  public String toString() {
    return "TopicMeta{"
        + "topicName='"
        + topicName
        + "', creationTime="
        + creationTime
        + ", config="
        + config
        + '}';
  }
@return true if the consumer group did not already subscribe this topic
iotdb-core/node-commons/src/main/java/org/apache/iotdb/commons/subscription/meta/topic/TopicMeta.java