public long lowestPossiblyFreeChunk() {
   if (tier == 0) {
     return segmentHeader.lowestPossiblyFreeChunk(segmentHeaderAddress);
   } else {
     return TierCountersArea.lowestPossiblyFreeChunkTiered(tierCountersAreaAddr());
   }
 }
 public void lowestPossiblyFreeChunk(long lowestPossiblyFreeChunk) {
   if (tier == 0) {
     segmentHeader.lowestPossiblyFreeChunk(segmentHeaderAddress, lowestPossiblyFreeChunk);
   } else {
     TierCountersArea.lowestPossiblyFreeChunkTiered(
         tierCountersAreaAddr(), lowestPossiblyFreeChunk);
   }
 }