boolean firstTimeSeen = seen.add(t);
      if (!firstTimeSeen) {
        /*
         * We've seen this, so we've seen its causes, too. No need to re-add them. (There's one case
         * where this isn't true, but we ignore it: If we record an exception, then someone calls
         * initCause() on it, and then we examine it again, we'll conclude that we've seen the whole
         * chain before when in fact we haven't. But this should be rare.)

          override fun authenticate(
            route: Route?,
            response: Response,
          ): Request? {
            if (response.request.header("Authorization") != null) {
              return null // Give up, we've already attempted to authenticate.
            }

            println("Authenticating for response: $response")
            println("Challenges: ${response.challenges()}")

          if (labels[currentLabelIndex].size == currentLabelByteIndex) {
            // We've exhausted our current label. Either there are more labels to compare, in which
            // case we expect a dot as the next character. Otherwise, we've checked all our labels.
            if (currentLabelIndex == labels.size - 1) {
              break
            } else {

   * range [0, k) and ignore the remaining elements.
   */
  private final @Nullable T[] buffer;
  private int bufferSize;

  /**
   * The largest of the lowest k elements we've seen so far relative to this comparator. If
   * bufferSize ≥ k, then we can ignore any elements greater than this value.
   */
  private @Nullable T threshold;

      value = (value shl 4) + hexDigit
      i++
    }
    val groupLength = i - groupOffset
    if (groupLength == 0 || groupLength > 4) return null // Group is the wrong size.

    // We've successfully read a group. Assign its value to our byte array.
    address[b++] = (value.ushr(8) and 0xff).toByte()
    address[b++] = (value and 0xff).toByte()
  }

  public Authenticate() {
    client = new OkHttpClient.Builder()
        .authenticator((route, response) -> {
          if (response.request().header("Authorization") != null) {
            return null; // Give up, we've already attempted to authenticate.
          }

          System.out.println("Authenticating for response: " + response);
          System.out.println("Challenges: " + response.challenges());

    val bufferB = Buffer()
    bufferA.writeUtf8("Dodgson!\n")
    operatorA.write(0, bufferA, 9)
    bufferB.writeUtf8("You shouldn't use my name.\n")
    operatorB.write(9, bufferB, 27)
    bufferA.writeUtf8("Dodgson, we've got Dodgson here!\n")
    operatorA.write(36, bufferA, 33)
    operatorB.read(0, bufferB, 9)
    assertThat(bufferB.readUtf8()).isEqualTo("Dodgson!\n")
    operatorA.read(9, bufferA, 27)

    while (hasNextProxy()) {
      // Postponed routes are always tried last. For example, if we have 2 proxies and all the
      // routes for proxy1 should be postponed, we'll move to proxy2. Only after we've exhausted
      // all the good routes will we attempt the postponed routes.
      val proxy = nextProxy()
      for (inetSocketAddress in inetSocketAddresses) {
        val route = Route(address, proxy, inetSocketAddress)

  static final String E15 = "1-5";
  static final String EDGE_NOT_IN_GRAPH = "edgeNotInGraph";

  // TODO(user): Consider separating Strings that we've defined here to capture
  // identifiable substrings of expected error messages, from Strings that we've defined
  // here to provide error messages.
  // TODO(user): Some Strings used in the subclasses can be added as static Strings
  // here too.

    `Request.Builder.url()` now throws `IllegalArgumentException` on malformed
    URLs. (Previous releases would throw a `MalformedURLException` when calling
    a malformed URL.)

 *  **We've improved connect failure recovery.** We now differentiate between
    setup, connecting, and connected and implement appropriate recovery rules
    for each. This changes `Address` to no longer use `ConnectionSpec`. (This is