public int getMaxIterationAcrossGroups() {
    return getGroupTrackers().stream().map(GroupTracker::getIterations).max(Comparator.naturalOrder()).orElse(0);
  }
@return Iterates over all group trackers and returns maximum iterations done by any group
ambry-replication/src/main/java/com/github/ambry/replication/continuous/DataNodeTracker.java