code: public static ReplayPosition getReplayPosition(Iterable<? extends SSTableReader> sstables)
      {
          if (Iterables.isEmpty(sstables))
              return NONE;
  
          Function<SSTableReader, ReplayPosition> f = new Function<SSTableReader, ReplayPosition>()
          {
              public ReplayPosition apply(SSTableReader sstable)
              {
                  return sstable.getReplayPosition();
              }
          };
          Ordering<ReplayPosition> ordering = Ordering.from(ReplayPosition.comparator);
          return ordering.max(Iterables.transform(sstables, f));
      }
docs: Convenience method to compute the replay position for a group of SSTables.
  @param sstables
  @return the most recent (highest) replay position