advice on upgrading from 1.x to 2.x.

 *  Fix: Don't leak connections! There was a regression in 2.0.0-RC1 where
    connections were neither closed nor pooled.
 *  Fix: Revert builder-style return types from OkHttpClient's timeout methods
    for binary compatibility with OkHttp 1.x.
 *  Fix: Don't skip client stream 1 on SPDY/3.1. This fixes SPDY connectivity to

   *
   * @param event event to post.
   */
  public void post(Object event) {
    Iterator<Subscriber> eventSubscribers = subscribers.getSubscribers(event);
    if (eventSubscribers.hasNext()) {
      dispatcher.dispatch(event, eventSubscribers);
    } else if (!(event instanceof DeadEvent)) {
      // the event had no subscribers and was not itself a DeadEvent
      post(new DeadEvent(this, event));
    }
  }

  @Override

  private static final ListenerCallQueue.Event<Listener> HEALTHY_EVENT =
      new ListenerCallQueue.Event<Listener>() {
        @Override
        public void call(Listener listener) {
          listener.healthy();
        }

        @Override
        public String toString() {
          return "healthy()";
        }
      };
  private static final ListenerCallQueue.Event<Listener> STOPPED_EVENT =

 *
 *  * When an entry is being **edited**, it is not necessary to supply data for every value; values
 *    default to their previous value.
 *
 * Every [edit] call must be matched by a call to [Editor.commit] or [Editor.abort]. Committing is
 * atomic: a read observes the full set of values as they were before or after the commit, but never
 * a mix of values.
 *

          interruptedDuringTask |= Thread.interrupted();
          try {
            task.run();
          } catch (Exception e) { // sneaky checked exception
            log.get().log(Level.SEVERE, "Exception while executing runnable " + task, e);
          } finally {
            task = null;
          }
        }
      } finally {

    // shouldn't break in cases where reflection is missing/broken.
    if (thrownAtomicReferenceFieldUpdaterFailure != null) {
      log.get().log(SEVERE, "UnsafeAtomicHelper is broken!", thrownUnsafeFailure);
      log.get()
          .log(
              SEVERE,
              "AtomicReferenceFieldUpdaterAtomicHelper is broken!",
              thrownAtomicReferenceFieldUpdaterFailure);
    }
  }

  private static final ListenerCallQueue.Event<Listener> TERMINATED_FROM_NEW_EVENT =
      terminatedEvent(NEW);
  private static final ListenerCallQueue.Event<Listener> TERMINATED_FROM_STARTING_EVENT =
      terminatedEvent(STARTING);
  private static final ListenerCallQueue.Event<Listener> TERMINATED_FROM_RUNNING_EVENT =
      terminatedEvent(RUNNING);
  private static final ListenerCallQueue.Event<Listener> TERMINATED_FROM_STOPPING_EVENT =

    // shouldn't break in cases where reflection is missing/broken.
    if (thrownAtomicReferenceFieldUpdaterFailure != null) {
      log.get().log(SEVERE, "UnsafeAtomicHelper is broken!", thrownUnsafeFailure);
      log.get()
          .log(
              SEVERE,
              "AtomicReferenceFieldUpdaterAtomicHelper is broken!",
              thrownAtomicReferenceFieldUpdaterFailure);
    }
  }

 * <p>This class has limited support for cancellation and other "early completions":
 *
 * <ul>
 *   <li>While calls to {@code submit} and {@code submitAsync} return a {@code Future} that can be
 *       cancelled, cancellation never propagates to a task that has started to run -- neither to
 *       the callable itself nor to any {@code Future} returned by an {@code AsyncCallable}.

 * your application's HTTP calls.
 *
 * All start/connect/acquire events will eventually receive a matching end/release event, either
 * successful (non-null parameters), or failed (non-null throwable). The first common parameters of
 * each event pair are used to link the event in case of concurrent or repeated events e.g.
 * `dnsStart(call, domainName)` → `dnsEnd(call, domainName, inetAddressList)`.
 *