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;

  /**

   * Foo<Enum<?>>} according to JLS. See testRecursiveWildcardSubtypeBug() for a real example.
   *
   * <p>It appears that properly handling recursive type bounds in the presence of implicit type
   * bounds is not easy. For now we punt, hoping that this defect should rarely cause issues in real
   * code.
   *

   * 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>