@Override
    public String toString() {
        return "GroupTopicPartitionData(" +
                "groupId=" + groupId + ", " +
                "topicsData=" + topicsData +
                ")";
    }
This class is used to contain the data for a group, a topic and its partitions in the interface to {@link Persister}.

@param <P> The type of {@link PartitionInfoData}
server-common/src/main/java/org/apache/kafka/server/group/share/GroupTopicPartitionData.java