@Override
    public void onElection(
        int groupMetadataPartitionIndex,
        int groupMetadataPartitionLeaderEpoch
    ) {
        throwIfNotActive();
        runtime.scheduleLoadOperation(
            new TopicPartition(Topic.GROUP_METADATA_TOPIC_NAME, groupMetadataPartitionIndex),
            groupMetadataPartitionLeaderEpoch
        );
    }
See {@link GroupCoordinator#onElection(int, int)}.
group-coordinator/src/main/java/org/apache/kafka/coordinator/group/GroupCoordinatorService.java