docs: public static FormValidation validateInternetAddress(String address) {
          if (Strings.isNullOrEmpty(address)) {
              return FormValidation.ok();
          }
          Matcher matcher = VALID_EMAIL_PATTERN.matcher(address);
          if (matcher.matches()) {
              return FormValidation.ok();
          } else {
              return FormValidation.error("Email address is invalid");
          }
      }