code: public SimpleDateFormat build() {
          
          final SimpleDateFormat formatter;
          if(locale == null) {
              formatter = new SimpleDateFormat(pattern);
          } else {
              formatter = new SimpleDateFormat(pattern, locale);
          }
          
          if(timeZone != null) {
              formatter.setTimeZone(timeZone);
          }
          formatter.setLenient(lenient);
          
          return formatter;
          
      }
docs: create instance {@link SimpleDateFormat}
  @return