code: public PactDslJsonArray stringMatcher(String regex, String value) {
          if (!value.matches(regex)) {
              throw new InvalidMatcherException(EXAMPLE + value + "\" does not match regular expression \"" +
                  regex + "\"");
          }
          body.put(value);
          matchers.addRule(rootPath + appendArrayIndex(0), regexp(regex));
          return this;
      }
docs: Element that must match the regular expression
  @param regex regular expression
  @param value example value to use for generated bodies