};
  }

  /**
   * Combines two iterators into a single iterator. The returned iterator iterates across the
   * elements in {@code a}, followed by the elements in {@code b}. The source iterators are not
   * polled until necessary.
   *
   * <p>The returned iterator supports {@code remove()} when the corresponding input iterator
   * supports it.
   */
  public static <T extends @Nullable Object> Iterator<T> concat(

  }

  /**
   * Combines two iterables into a single iterable. The returned iterable has an iterator that
   * traverses the elements in {@code a}, followed by the elements in {@code b}. The source
   * iterators are not polled until necessary.
   *
   * <p>The returned iterable's iterator supports {@code remove()} when the corresponding input
   * iterator supports it.
   *

      expected.assertSuppressed { throwables: List<Throwable>? ->
        assertThat(throwables!!.size).isEqualTo(1)
      }
    }
  }

  /**
   * When a pooled connection fails, don't blame the route. Otherwise pooled connection failures can
   * cause unnecessary SSL fallbacks.
   *
   * https://github.com/square/okhttp/issues/515
   */
  @Test
  fun sslFallbackNotUsedWhenRecycledConnectionFails() {

   *
   * This can be invoked more than 1 time for a single [Call]. For example, if the response to the
   * [Call.request] is a redirect to a different host.
   *
   * If the [Call] is able to reuse an existing pooled connection, this method will not be invoked.
   * See [ConnectionPool].
   */
  open fun dnsStart(
    call: Call,
    domainName: String,
  ) {
  }

  /**

    different cipher suite than before! OkHttp's defaults cipher suites are selected for good
    security and performance.

 *  New: `ConnectionListener` publishes events for connects, disconnects, and use of pooled
    connections.

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

  @Override
  protected char @Nullable [] escape(int cp) {
    // We should never get negative values here but if we do it will throw an
    // IndexOutOfBoundsException, so at least it will get spotted.
    if (cp < safeOctets.length && safeOctets[cp]) {
      return null;
    } else if (cp == ' ' && plusForSpace) {
      return plusSign;
    } else if (cp <= 0x7F) {
      // Single byte UTF-8 characters

 *  New: `ConnectionSpec.isCompatible(SSLSocket)`.
 *  New: `Dispatcher.getQueuedCallCount()` and
    `Dispatcher.getRunningCallCount()`. These can be useful in diagnostics.
 *  Fix: OkHttp no longer shares timeouts between pooled connections. This was
    causing some applications to crash when connections were reused.
 *  Fix: `OkApacheClient` now allows an empty `PUT` and `POST`.
 *  Fix: Websockets no longer rebuffer socket streams.

        nonPooledConnections.forEach(conn -> {
            try {
                conn.disconnect(true, true);
            } catch (Exception e) {
                log.debug("Error closing non-pooled connection: {}", e.getMessage());
            }
        });
        nonPooledConnections.clear();

        activeConnections.set(0);
        log.info("Transport pool closed");
    }

    /**

        when {
          client.fastFallback -> FastFallbackExchangeFinder(routePlanner, client.taskRunner)
          else -> SequentialExchangeFinder(routePlanner)
        }
    }
  }

  /** Finds a new or pooled connection to carry a forthcoming request and response. */
  internal fun initExchange(chain: RealInterceptorChain): Exchange {
    withLock {
      check(expectMoreExchanges) { "released" }
      check(!responseBodyOpen)

    )

    taskFaker.assertNoMoreTasks()
  }

  /**
   * This test causes two connections to become available simultaneously, one from a TCP connect and
   * one from the pool. We must take the pooled connection because by taking it from the pool, we've
   * fully acquired it.
   *
   * This test yields threads to force the decision of plan1 to be deliberate and not lucky. In