class PartitionGroup {

    long partitionTimestamp(final TopicPartition partition) {
        final RecordQueue queue = partitionQueues.get(partition);
        if (queue == null) {
            throw new IllegalStateException("Partition " + partition + " not found.");
        }
        return queue.partitionTime();
    }

      PartitionGroup(final Map<TopicPartition, RecordQueue> partitionQueues, final Sensor recordLatenessSensor);

}