code: public DateTimeFormatter withDecimalStyle(DecimalStyle decimalStyle) {
          if (this.decimalStyle.equals(decimalStyle)) {
              return this;
          }
          return new DateTimeFormatter(printerParser, locale, decimalStyle, resolverStyle, resolverFields, chrono, zone);
      }
docs: Returns a copy of this formatter with a new DecimalStyle.
  <p>
  This instance is immutable and unaffected by this method call.
  
  @param decimalStyle  the new DecimalStyle, not null
  @return a formatter based on this formatter with the requested DecimalStyle, not null