* | `http://127.0.0.1`            | null                 |
   */
  fun topPrivateDomain(): String? {
    return if (host.canParseAsIpAddress()) {
      null
    } else {
      PublicSuffixDatabase.get().getEffectiveTldPlusOne(host)
    }
  }

  @JvmName("-deprecated_url")
  @Deprecated(
    message = "moved to toUrl()",
    replaceWith = ReplaceWith(expression = "toUrl()"),
    level = DeprecationLevel.ERROR,
  )