_2019-03-14_

 *  **This release deletes the long-deprecated `OkUrlFactory` and `OkApacheClient` APIs.** These
    facades hide OkHttp's implementation behind another client's API. If you still need this please
    copy and paste [ObsoleteUrlFactory.java][obsolete_url_factory] or
    [ObsoleteApacheClient.java][obsolete_apache_client] into your project.

 *  **OkHttp now supports duplex calls over HTTP/2.** With normal HTTP calls the request must finish

   * uniform, the actual concurrency observed may vary. Ideally, you should choose a value to
   * accommodate as many threads as will ever concurrently modify the table. Using a significantly
   * higher value than you need can waste space and time, and a significantly lower value can lead
   * to thread contention. But overestimates and underestimates within an order of magnitude do not

          throw new NoSuchElementException();
        }
        /*
         * requireNonNull is safe because our callers always pass non-null arguments. Each element
         * of the array becomes null only when we iterate past it and then clear it.
         */
        I result = requireNonNull(elements[index]);
        elements[index] = null;
        index++;
        return result;
      }
    };
  }

  /**

   * checkNotNull *should* be annotated to require it to be non-null.
   *
   * However, for a variety of reasons, Google developers have written a ton of code over the past
   * decade that assumes that they can use checkNotNull for non-precondition checks. I had hoped to
   * take a principled stand on this, but the amount of such code is simply overwhelming. To avoid