code: public PactDslJsonArray timestamp(String format, Instant example) {
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern(format);
        body.put(formatter.format(example));
        matchers.addRule(rootPath + appendArrayIndex(0), matchTimestamp(format));
        return this;
      }
docs: Element that must match the given timestamp format
  @param format timestamp format
  @param example example date and time to use for generated bodies