*       </ul>
   *   <li>another java.util.Map delegate implementation. In most modern JDKs, normal java.util hash
   *       collections intelligently fall back to a binary search tree if hash table collisions are
   *       detected. Rather than going to all the trouble of reimplementing this ourselves, we
   *       simply switch over to use the JDK implementation wholesale if probable hash flooding is

_2019-09-29_

 *  Fix: Cancel calls that fail due to unexpected exceptions. We had a bug where an enqueued call
    would never call back if it crashed with an unchecked throwable, such as a
    `NullPointerException` or `OutOfMemoryError`. We now call `Callback.onFailure()` with an
    `IOException` that reports the call as canceled. The triggering exception is still delivered to
    the thread's `UncaughtExceptionHandler`.

        }
      }
    } else {
      /*
       * We'll call the user callback or collect the values only when all inputs complete,
       * regardless of whether some failed. This lets us avoid calling expensive methods like
       * Future.get() when we don't need to (specifically, for whenAllComplete().call*()), and it
       * lets all futures share the same listener.
       *

   * value. Otherwise, a call that passes one {@code loader} may return the result of another call
   * with a differently behaving {@code loader}. For example, a call that requests a short timeout
   * for an RPC may wait for a similar call that requests a long timeout, or a call by an
   * unprivileged user may return a resource accessible only to a privileged user making a similar

   * value. Otherwise, a call that passes one {@code loader} may return the result of another call
   * with a differently behaving {@code loader}. For example, a call that requests a short timeout
   * for an RPC may wait for a similar call that requests a long timeout, or a call by an
   * unprivileged user may return a resource accessible only to a privileged user making a similar

   *
   * 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 address.
   */
  open fun connectionAcquired(
    call: Call,
    connection: Connection,
  ) {
  }

  /**
   * Invoked after a connection has been released for the `call`.
   *

    /**
     * It is implicitly assumed that all the services are NEW and that they will all remain NEW
     * until all the Listeners are installed and {@link #markReady()} is called. It is our caller's
     * responsibility to only call {@link #markReady()} if all services were new at the time this
     * method was called and when all the listeners were installed.
     */

     * we must return it in the following next() call even if it was in the process of being removed
     * when hasNext() was called.
     */
    private @Nullable E nextItem;

    /**
     * Index of element returned by most recent call to next. Reset to -1 if this element is deleted
     * by a call to remove.
     */
    private int lastRet;

    Itr() {
      lastRet = -1;

     *     {@link #whenAllComplete(Iterable)} or {@link #whenAllComplete(Iterable)}
     * @throws IllegalStateException if called outside of a call to {@link
     *     CombiningCallable#call(DeferredCloser, Peeker)} or {@link
     *     AsyncCombiningCallable#call(DeferredCloser, Peeker)}
     */
    @ParametricNullness
    public final <D extends @Nullable Object> D getDone(ClosingFuture<D> closingFuture)

   * trailers are available to read.
   *
   * It is not safe to call this concurrently with code that is processing the response body. If you
   * call this without consuming the complete response body, any remaining bytes in the response
   * body will be discarded before trailers are returned.
   *
   * If [Call.cancel] is called while this is blocking, this call will immediately throw.
   *