.isEqualTo("xn--ewv.xn--4pvxs.jp")
    assertThat("https://co.uk".toHttpUrl().topPrivateDomain()).isNull()
    assertThat("https://square".toHttpUrl().topPrivateDomain()).isNull()
    assertThat("https://栃木.jp".toHttpUrl().topPrivateDomain()).isNull()
    assertThat("https://xn--4pvxs.jp".toHttpUrl().topPrivateDomain()).isNull()
    assertThat("https://localhost".toHttpUrl().topPrivateDomain()).isNull()

    InternetDomainName googleDomain = InternetDomainName.from("google.com");

    assertEquals(googleDomain, googleDomain.topPrivateDomain());
    assertEquals(googleDomain, googleDomain.child("mail").topPrivateDomain());
    assertEquals(googleDomain, googleDomain.child("foo.bar").topPrivateDomain());
  }

  public void testInvalidTopPrivateDomain() {

 *  Fix: Recover gracefully when a cache entry's certificate is corrupted.

 *  Fix: Fail permanently when there's a failure loading the bundled public suffix database.
    This is the dataset that powers `HttpUrl.topPrivateDomain()`.

 *  Fix: Immediately update the connection's flow control window instead of waiting for the
    receiving stream to process it.

   * controls.
   *
   * @throws IllegalStateException if this domain does not end with a public suffix
   * @since 6.0
   */
  public InternetDomainName topPrivateDomain() {
    if (isTopPrivateDomain()) {
      return this;
    }
    checkState(isUnderPublicSuffix(), "Not under a public suffix: %s", name);
    return ancestor(publicSuffixIndex() - 1);
  }

  /**

   * controls.
   *
   * @throws IllegalStateException if this domain does not end with a public suffix
   * @since 6.0
   */
  public InternetDomainName topPrivateDomain() {
    if (isTopPrivateDomain()) {
      return this;
    }
    checkState(isUnderPublicSuffix(), "Not under a public suffix: %s", name);
    return ancestor(publicSuffixIndex() - 1);
  }

  /**

    val redact: String = httpUrl.redact()
    var builder: HttpUrl.Builder = httpUrl.newBuilder()
    var resolveBuilder: HttpUrl.Builder? = httpUrl.newBuilder("")
    val topPrivateDomain: String? = httpUrl.topPrivateDomain()
    val resolve: HttpUrl? = httpUrl.resolve("")
    val getFromUrl: HttpUrl? = URL("").toHttpUrlOrNull()
    val getFromUri: HttpUrl? = URI("").toHttpUrlOrNull()

  @get:JvmName("hostOnly") val hostOnly: Boolean,
  /**
   * Returns a string describing whether this cookie is sent for cross-site calls.
   *
   * Two URLs are on the same site if they share a [top private domain][HttpUrl.topPrivateDomain].
   * Otherwise, they are cross-site URLs.
   *
   * When a URL is requested, it may be in the context of another URL.
   *

    attempt multiple TLS handshakes for the same call concurrently.
 *  Fix: Don't crash loading the public suffix database in GraalVM native images. The function
    `HttpUrl.topPrivateDomain()` uses a resource file to identify private domains, but we didn't
    include this file on GraalVM.


## Version 5.0.0-alpha.4

_2022-02-01_