code: public Stopwatch stop() {
          if (!myTimerIsRunning) {
              throw new IllegalStateException(LOGGER.getI18n(MessageCodes.UTIL_041));
          }
  
          myStop = System.currentTimeMillis();
          myTimerIsRunning = false;
  
          return this;
      }
docs: Stop the stopwatch.
  
  @throws IllegalStateException if the stopwatch is not already running.
  @return The stopwatch