private @Nullable T nextOrNull;

  /**
   * Creates a new iterator with the given first element, or, if {@code firstOrNull} is null,
   * creates a new empty iterator.
   */
  protected AbstractSequentialIterator(@Nullable T firstOrNull) {
    this.nextOrNull = firstOrNull;
  }

  /**
   * Returns the element that follows {@code previous}, or returns {@code null} if no elements

    val issuer = cert.issuerX500Principal
    val subjectCaCerts = subjectToCaCerts[issuer] ?: return null

    return subjectCaCerts.firstOrNull {
      try {
        cert.verify(it.publicKey)
        return@firstOrNull true
      } catch (_: Exception) {
        return@firstOrNull false
      }
    }
  }

  override fun equals(other: Any?): Boolean =
    other === this ||

  private @Nullable T nextOrNull;

  /**
   * Creates a new iterator with the given first element, or, if {@code firstOrNull} is null,
   * creates a new empty iterator.
   */
  protected AbstractSequentialIterator(@Nullable T firstOrNull) {
    this.nextOrNull = firstOrNull;
  }

  /**
   * Returns the element that follows {@code previous}, or returns {@code null} if no elements

  /** Returns the remote peer's principle, or null if that peer is anonymous. */
  @get:JvmName("peerPrincipal")
  val peerPrincipal: Principal?
    get() = (peerCertificates.firstOrNull() as? X509Certificate)?.subjectX500Principal

  @JvmName("-deprecated_peerPrincipal")
  @Deprecated(
    message = "moved to val",
    replaceWith = ReplaceWith(expression = "peerPrincipal"),

  return SuiteId(id, matcher.groupValues[3])
}

class IanaSuites(
  val name: String,
  val suites: List<SuiteId>,
) {
  fun fromJavaName(javaName: String): SuiteId =
    suites.firstOrNull {
      it.name == javaName || it.name == "TLS_${javaName.drop(4)}"
    } ?: throw IllegalArgumentException("No such suite: $javaName")
}

suspend fun fetchIanaSuites(okHttpClient: OkHttpClient): IanaSuites {

  @BeforeEach
  internal fun setUp() {
    val inetAddresses = InetAddress.getAllByName("localhost")
    localhostIpv4 = inetAddresses.firstOrNull { it is Inet4Address }
      ?: throw TestAbortedException()
    localhostIpv6 = inetAddresses.firstOrNull { it is Inet6Address }
      ?: throw TestAbortedException()

    serverIpv4 = MockWebServer()
    serverIpv4.start(localhostIpv4, 0) // Pick any available port.

    return OkHttpDebugLogging.enable(
      "javax.net.ssl",
      object : Handler() {
        override fun publish(record: LogRecord) {
          val param = record.parameters?.firstOrNull() as? String
          debugHandler(JsseDebugMessage(record.message, param))
        }

        override fun flush() {
        }

        override fun close() {
        }
      },
    )
  }