code: public static PactDslRootValue timestamp(String format) {
      PactDslRootValue value = new PactDslRootValue();
      value.generators.addGenerator(Category.BODY, "", new DateTimeGenerator(format));
      FastDateFormat instance = FastDateFormat.getInstance(format);
      value.setValue(instance.format(new Date(DATE_2000)));
      value.setMatcher(value.matchTimestamp(format));
      return value;
    }
docs: Value that must match the given timestamp format
  @param format timestamp format