docs: double bytesPerSecond(double byteCount, double durationNano) {
          if (byteCount < 0 || durationNano < 0)
              throw new IllegalArgumentException();
          if (durationNano == 0) {
              durationNano = 1.0;   // defend against division by zero
              if (log.isDebugEnabled()) {
                  log.debug("Set zero to one to avoid division by zero; but should never get here!");
              }
          }
          double bytesPerSec = (byteCount / durationNano) * NANO_PER_SEC;
          if (bytesPerSec == 0) {
              if (log.isDebugEnabled()) {
                  log.debug("zero bytes per sec.  Really ?");
              }
          }
          return bytesPerSec;
      }