// final fields.
  //
  // For simplicity the rest of this description will discuss Futures.catching since it is the
  // simplest instance, though very similar descriptions apply to many other classes in this file.
  //
  // In the constructor of AbstractCatchingFuture, the delegate future is assigned to a field

   *   method-reference linking tries to look up the system classloader, and it fails because there
   *   isn't one yet.
   *
   * - lambda: Outside Google, we got a report of a similar problem in
   *   https://github.com/google/guava/issues/6565
   */
  @SuppressWarnings("AnonymousToLambda")
  static final Supplier<StatsCounter> CACHE_STATS_COUNTER =
      new Supplier<StatsCounter>() {

   * rate, and ability to be implemented with O(1) time complexity. The initial LRU implementation
   * operates per-segment rather than globally for increased implementation simplicity. We expect
   * the cache hit rate to be similar to that of a global LRU algorithm.
   */

  // Constants

  /**
   * The maximum capacity, used if a higher value is implicitly specified by either of the

   * an element in the set. For example, {@code contains} returns {@code false} when passed an
   * object that equals a set member, but isn't the same instance. This behavior is similar to the
   * way {@code IdentityHashMap} handles key lookups.
   *
   * @since 8.0
   */
  public static <E extends @Nullable Object> Set<E> newIdentityHashSet() {

 * example, the Unicode trademark sign (™) could be confused for the letters "TM" in
 * `http://ho™ail.com`. To mitigate this, the single character (™) maps to the string (tm). There
 * is similar policy for all of the 1.1 million Unicode code points. Note that some code points such
 * as "\ud83c\udf69" are not mapped and cannot be used in a hostname.
 *

 * href="https://github.com/google/guava/wiki/ConditionalFailuresExplained">Conditional failures
 * explained</a> in the Guava User Guide for more advice. Notably, {@link Verify} offers assertions
 * similar to those in this class for non-precondition checks.
 *
 * <h3>{@code java.util.Objects.requireNonNull()}</h3>
 *
 * <p>Projects which use {@code com.google.common} should generally avoid the use of {@link

      Thread.sleep(2000L)
    }
    if (connection.isHealthy(false)) {
      throw TimeoutException("connection didn't shutdown within timeout")
    }
  }

  /**
   * This simulates a race condition where we receive a healthy HTTP/2 connection and just prior to
   * writing our request, we get a GOAWAY frame from the server.
   */
  @ParameterizedTest
  @ArgumentsSource(ProtocolParamProvider::class)

    as modern web browsers.

 *  **Form and Multipart bodies are now modeled.** We've replaced the opaque
    `FormEncodingBuilder` with the more powerful `FormBody` and
    `FormBody.Builder` combo. Similarly we've upgraded `MultipartBuilder` into
    `MultipartBody`, `MultipartBody.Part`, and `MultipartBody.Builder`.

 *  **The Apache HTTP client and HttpURLConnection APIs are deprecated.** They