private static final ImmutableSet<String> RS =
      ImmutableSet.of(
          // keep-sorted start
          "\u7f51\u7edc.Cn", // "网络.Cn"
          "co.uk",
          "co.uk.", // Trailing dot
          "co\uFF61uk", // Alternate dot character
          "com",
          "foo.bd",
          "org.mK",
          "us",
          "xxxxxx.bd",
          // keep-sorted end

  }

  private fun splitDomain(domain: String): List<String> {
    val domainLabels = domain.split('.')

    if (domainLabels.last() == "") {
      // allow for domain name trailing dot
      return domainLabels.dropLast(1)
    }

    return domainLabels
  }

  private fun findMatchingRule(domainLabels: List<String>): List<String> {
    publicSuffixList.ensureLoaded()

 * lookups.
 *
 * <p>During construction, names are normalized in two ways:
 *
 * <ol>
 *   <li>ASCII uppercase characters are converted to lowercase.
 *   <li>Unicode dot separators other than the ASCII period ({@code '.'}) are converted to the ASCII
 *       period.
 * </ol>
 *
 * <p>The normalized values will be returned from {@link #toString()} and {@link #parts()}, and will

- Promoted `RelaxedDNSSearchValidation` to beta, allowing for Pod search domains to be a single dot "." or contain an underscore "_". ([#130128](https://github.com/kubernetes/kubernetes/pull/130128), [@adrianmoisey](https://github.com/adrianmoisey)) [SIG Apps and Network]

- Graduated relaxed DNS search string validation to GA. For the Pod API, `.spec.dnsConfig.searches`
  now allows an underscore (`_`) where a dash (`-`) would be allowed, and it allows search strings be a single dot `.`. ([#132036](https://github.com/kubernetes/kubernetes/pull/132036), [@adrianmoisey](https://github.com/adrianmoisey)) [SIG Network and Testing]

- Allow for Pod search domains to be a single dot `.` or contain an underscore `_` ([#127167](https://github.com/kubernetes/kubernetes/pull/127167), [@adrianmoisey](https://github.com/adrianmoisey)) [SIG Apps, Network and Testing]