code: @Nonnull
    public static ESuccess setDefaultDateTimeZoneID (@Nonnull @Nonempty final String sDateTimeZoneID)
    {
      ValueEnforcer.notEmpty (sDateTimeZoneID, "DateTimeZoneID");
  
      try
      {
        // Try to resolve ID -> throws exception if unknown
        final ZoneId aDefaultZoneId = ZoneId.of (sDateTimeZoneID);
  
        // getTimeZone falls back to GMT if unknown
        final TimeZone aDefaultTimeZone = TimeZone.getTimeZone (aDefaultZoneId);
  
        s_aDefaultZoneId = aDefaultZoneId;
        TimeZone.setDefault (aDefaultTimeZone);
        return ESuccess.SUCCESS;
      }
      catch (final DateTimeException ex)
      {
        // time zone ID is unknown
        LOGGER.warn ("Unsupported ZoneId '" + sDateTimeZoneID + "'", ex);
        return ESuccess.FAILURE;
      }
    }
docs: Set the default date time zone to use. This effects all objects created via
  {@link PDTFactory} as well as the default JDK TimeZone.
  
  @param sDateTimeZoneID
  Must be a valid, non-<code>null</code> time zone.
  @return {@link ESuccess}