docs: private void calculateTrackers(Collection<TopicPartition> partitions) {
  
          Map<TopicPartition, CommitTracker> trackers = new HashMap<>();
          trackers.putAll(m_trackerMap.get());
  
          Map<TopicPartition, AtomicLong> lastCommittedOffSets = new HashMap<>();
          lastCommittedOffSets.putAll(m_lastCommittedOffSets.get());
  
          boolean newTopicPartition = false;
          for (TopicPartition partition : partitions) {
              if (m_trackerMap.get().get(partition) != null) {
                  continue;
              }
              newTopicPartition = true;
              long startOffset = -1L;
              CommitTracker commitTracker = null;
              if (m_config.getCommitPolicy() == KafkaCommitPolicy.TIME && m_config.getTriggerValue() > 0) {
                  commitTracker = new SimpleTracker();
              } else {
                  commitTracker = new DurableTracker(KafkaConstants.IMPORT_GAP_LEAD, partition.topic(),
                          partition.partition(), m_config.getGroupId());
              }
              trackers.put(partition, commitTracker);
              try {
                  OffsetAndMetadata offsetAndMetaData = m_consumer.committed(partition);
                  startOffset = offsetAndMetaData != null ? offsetAndMetaData.offset() : -1L;
                  if (startOffset > -1L) {
                      commitTracker.resetTo(startOffset);
                  }
              } catch (KafkaException e) {
                  LOGGER.error("Failed to read committed offsets for group " + m_config.getGroupId() + partition + " " + e.getMessage());
              }
              lastCommittedOffSets.put(partition, new AtomicLong(startOffset));
              m_pauseOffsets.put(partition, new AtomicLong(-1));
              m_workTrackers.put(partition, new PendingWorkTracker());
              if (LOGGER.isDebugEnabled()) {
                  LOGGER.debug("Starting offset for group:" + m_config.getGroupId() + ":" + startOffset + " partition:" + partition);
              }
          }
          if (newTopicPartition) {
              m_trackerMap.set(trackers);
              m_lastCommittedOffSets.set(lastCommittedOffSets);
          }
      }