client.newBuilder()
        .sslSocketFactory(handshakeCertificates.sslSocketFactory())
    }
  }

  /** Confirm that runtime exceptions thrown inside of OkHttp propagate to the caller.  */
  @Test
  fun unexpectedExceptionSync() {
    client =
      client.newBuilder()
        .dns { hostname: String? -> throw RuntimeException("boom!") }
        .build()

   * have been received. If the returned list contains multiple blocks of headers the blocks will be
   * delimited by 'null'.
   *
   * @param callerIsIdle true if the caller isn't sending any more bytes until the peer responds.
   *     This is true after a `Expect-Continue` request, false for duplex requests, and false for
   *     all other requests.
   */
  @Throws(IOException::class)

   * auth param in the challenge at key null. Invalid headers and challenges are ignored.
   * No semantic validation is done, for example that `Basic` auth must have a `realm`
   * auth param, this is up to the caller that interprets these challenges.
   */
  fun challenges(): List<Challenge> {
    return headers.parseChallenges(
      when (code) {
        HTTP_UNAUTHORIZED -> "WWW-Authenticate"

  }

  /**
   * Callers of this method are not thread safe, and sometimes on application threads. Most often,
   * this method will be called to send a buffer worth of data to the peer.
   *
   * Writes are subject to the write window of the stream and the connection. Until there is a
   * window sufficient to send [byteCount], the caller will block. For example, a user of

    Arrays.fill(array, c)
    return String(array)
  }

  /**
   * Okio buffers are internally implemented as a linked list of arrays. Usually this implementation
   * detail is invisible to the caller, but subtle use of certain APIs may depend on these internal
   * structures.
   *
   * We make such subtle calls in [okhttp3.internal.ws.MessageInflater] because we try to read a

import okio.IOException

interface Callback {
  /**
   * Called when the request could not be executed due to cancellation, a connectivity problem or
   * timeout. Because networks can fail during an exchange, it is possible that the remote server
   * accepted the request before the failure.
   */
  fun onFailure(
    call: Call,
    e: IOException,
  )

  /**

    }
  }

  private fun logEvent(e: ConnectionEvent) {
    if (e.connection != null) {
      assertThat(Thread.holdsLock(e.connection), "Called with lock $${e.connection}")
        .isFalse()
    }
    for (lock in forbiddenLocks) {
      assertThat(Thread.holdsLock(lock), "Called with lock $lock")
        .isFalse()
    }

    if (enforceOrder) {
      checkForStartEvent(e)
    }

  fun metadata(): ByteString = metadata

  /**
   * Returns a new source that returns the same bytes as upstream. Returns null if this relay has
   * been closed and no further sources are possible. In that case callers should retry after
   * building a new relay with [.read].
   */
  fun newSource(): Source? {
    synchronized(this@Relay) {
      if (file == null) return null
      sourceCount++
    }

   * project's build file due to the dependency resolution features of your build tool.
   *
   * [semver]: https://semver.org
   */
  @Suppress("MayBeConstant") // Non-const so external callers get the runtime version.
  @JvmField
  val VERSION = CONST_VERSION

      } else {
        return EventListener.NONE;
      }
    }
  };

  ...
}
```

### Events with Failures

When an operation fails, a failure method is called. This is `connectFailed()` for failures while building a connection to the server, and `callFailed()` when the HTTP call fails permanently. When a failure happens it is possible that a `start` event won’t have a corresponding `end` event.