code: static synchronized TimeZone getDefaultRef() {
          if (defaultTimeZone == null) {
              defaultTimeZone = NativeTimeZone.getDefaultNativeTimeZone();
          }
  
          if (defaultTimeZone == null) {
              defaultTimeZone = GMTHolder.INSTANCE;
          }
  
          return defaultTimeZone;
      }
docs: Returns the reference to the default TimeZone object. This
  method doesn't create a clone.