* the returned {@code ListeningExecutorService} never calls the delegate's {@code submit}, {@code
   * invokeAll}, and {@code invokeAny} methods, so any special handling of tasks must be implemented
   * in the delegate's {@code execute} method or by wrapping the returned {@code
   * ListeningExecutorService}.
   *

          SetFuture<?> setFuture = (SetFuture<?>) task;
          // We unwind setFuture specifically to avoid StackOverflowErrors in the case of long
          // chains of SetFutures
          // Handling this special case is important because there is no way to pass an executor to
          // setFuture, so a user couldn't break the chain by doing this themselves.  It is also

  /** The concurrency level. */
  final int concurrencyLevel;

  /** Strategy for comparing keys. */
  final Equivalence<Object> keyEquivalence;

  /** Strategy for handling entries and segments in a type-safe and efficient manner. */
  final transient InternalEntryHelper<K, V, E, S> entryHelper;

  /**

  //     Ordering.<String>natural().lexicographical();
  public <S extends T> Ordering<Iterable<S>> lexicographical() {
    /*
     * Note that technically the returned ordering should be capable of
     * handling not just {@code Iterable<S>} instances, but also any {@code
     * Iterable<? extends S>}. However, the need for this comes up so rarely
     * that it doesn't justify making everyone else deal with the very ugly
     * wildcard.

   * a checked exception. This makes {@code Future} more suitable for lightweight, fast-running
   * tasks that, barring bugs in the code, will not fail. This gives it exception-handling behavior
   * similar to that of {@code ForkJoinTask.join}.
   *
   * <p>Exceptions from {@code Future.get} are treated as follows:
   *
   * <ul>

   *
   * @since 32.0.0
   */
  public static final String OBSERVE_BROWSING_TOPICS = "Observe-Browsing-Topics";

  /**
   * The HTTP <a
   * href="https://wicg.github.io/turtledove/#handling-direct-from-seller-signals">{@code
   * Sec-Ad-Auction-Fetch}</a> header field name.
   *
   * @since 33.0.0
   */
  public static final String SEC_AD_AUCTION_FETCH = "Sec-Ad-Auction-Fetch";

  /**