@Override
    public Set<String> getOfflineGroups() {
        Map<String, Set<String>> totalGroups =
                this.fileOffsetStorage.queryGroupTopicInfo(null);
        Set<String> offlineGroups = new HashSet<>(totalGroups.keySet());
        offlineGroups.removeAll(this.cfmOffsetMap.keySet());
        return offlineGroups;
    }
Get the offline group set

@return  the offline group set
inlong-tubemq/tubemq-server/src/main/java/org/apache/inlong/tubemq/server/broker/offset/DefaultOffsetManager.java