code: final private void updateWaterMark() {
          if (initWaterMark) {
              if (current < lowWaterMark)
                  lowWaterMark = current;
  
              if (current > highWaterMark)
                  highWaterMark = current;
          } else {
              lowWaterMark = highWaterMark = current;
              initWaterMark = true;
          }
      }
docs: Internal final method for perfOptimization