code: public Stopwatch start() {
          if (myTimerIsRunning) {
              throw new IllegalStateException(LOGGER.getI18n(MessageCodes.UTIL_040));
          }
  
          myStart = System.currentTimeMillis();
          myTimerIsRunning = true;
  
          return this;
      }
docs: Start the stopwatch.
  
  @throws IllegalStateException if the stopwatch is already running.
  @return The stopwatch