code: @Nonnull
    public static DateTimeFormatter getDateTimeFormatterSmart (@Nonnull @Nonempty final String sPattern)
    {
      return getDateTimeFormatter (sPattern, ResolverStyle.SMART);
    }
docs: Get the cached DateTimeFormatter using SMART resolving.
  
  @param sPattern
  The pattern to retrieve. May neither be <code>null</code> nor empty.
  @return The compiled DateTimeFormatter and never <code>null</code> .
  @throws IllegalArgumentException
  If the pattern is invalid