code: public static Stopwatch start(MonitorConfig config, TimeUnit unit) {
      return INSTANCE.get(config, unit).start();
    }
docs: Returns a stopwatch that has been started and will automatically
  record its result to the dynamic timer specified by the given config.
  
  @param config Config to identify a particular timer instance to update.
  @param unit   The unit to use when reporting values to observers. For example if sent to
  a typical time series graphing system this would be the unit for the y-axis.
  It is generally recommended to use base units for reporting, so
  {@link TimeUnit#SECONDS} is the preferred value.