throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2, p3, p4));
    }
  }

  /**
   * Ensures the truth of an expression involving the state of the calling instance, but not
   * involving any parameters to the calling method.
   *
   * @param expression a boolean expression
   * @throws IllegalStateException if {@code expression} is false
   * @see Verify#verify Verify.verify()
   */

   * RuntimeException}, {@link Error}, or {@code declaredType}.
   *
   * <p><b>Discouraged</b> in favor of calling {@link #throwIfInstanceOf} and {@link
   * #throwIfUnchecked}.
   *
   * @param throwable the Throwable to possibly propagate
   * @param declaredType the single checked exception type declared by the calling method
   * @deprecated Use a combination of {@link #throwIfInstanceOf} and {@link #throwIfUnchecked},

   * RuntimeException}, {@link Error}, or {@code declaredType}.
   *
   * <p><b>Discouraged</b> in favor of calling {@link #throwIfInstanceOf} and {@link
   * #throwIfUnchecked}.
   *
   * @param throwable the Throwable to possibly propagate
   * @param declaredType the single checked exception type declared by the calling method
   * @deprecated Use a combination of {@link #throwIfInstanceOf} and {@link #throwIfUnchecked},

      int j = findNextJ();
      if (j == -1) {
        nextPermutation = null;
        return;
      }
      /*
       * requireNonNull is safe because we don't clear nextPermutation until we're done calling this
       * method.
       */
      requireNonNull(nextPermutation);

      int l = findNextL(j);
      Collections.swap(nextPermutation, j, l);
      int n = nextPermutation.size();

    }

    private static final long serialVersionUID = 0;
  }

  /**
   * Returns a supplier whose {@code get()} method synchronizes on {@code delegate} before calling
   * it, making it thread-safe.
   */
  public static <T extends @Nullable Object> Supplier<T> synchronizedSupplier(
      Supplier<T> delegate) {
    return new ThreadSafeSupplier<>(delegate);
  }

   *
   * <p>The returned iterable's iterator supports {@code remove()} if the iterator of the underlying
   * iterable supports it. Note that it is <i>not</i> possible to delete the last skipped element by
   * immediately calling {@code remove()} on that iterator, as the {@code Iterator} contract states
   * that a call to {@code remove()} before a call to {@code next()} will throw an {@link
   * IllegalStateException}.
   *

     * multiset.
     *
     * Most code that operates on an AvlNode never operates on the header node. Such code can access
     * the elem field without a null check by calling getElement().
     */
    @CheckForNull private final E elem;

    // elemCount is 0 iff this node has been deleted.
    private int elemCount;

    private int distinctElements;

   * note that the execution order of all listeners is ultimately chosen by the implementations of
   * the supplied executors.
   *
   * <p>This method is idempotent. Calling it several times in parallel is semantically equivalent
   * to calling it exactly once.
   *
   * @since 10.0 (present in 1.0 as {@code run})
   */
  public void execute() {

        return new ImmutableEnumSet<>(set);
    }
  }

  /*
   * Notes on EnumSet and <E extends Enum<E>>:
   *
   * This class isn't an arbitrary ForwardingImmutableSet because we need to
   * know that calling {@code clone()} during deserialization will return an
   * object that no one else has a reference to, allowing us to guarantee
   * immutability. Hence, we support only {@link EnumSet}.
   */

    node.thread = null; // mark as 'deleted'
    restart:
    while (true) {
      Waiter pred = null;
      Waiter curr = waiters;
      if (curr == Waiter.TOMBSTONE) {
        return; // give up if someone is calling complete
      }
      Waiter succ;
      while (curr != null) {
        succ = curr.next;
        if (curr.thread != null) { // we aren't unlinking this node, update pred.
          pred = curr;