if (remainingNanos < SPIN_THRESHOLD_NANOS) {
                // Remove the waiter, one way or another we are done parking this thread.
                removeWaiter(node);
                break long_wait_loop; // jump down to the busy wait loop
              }
            }
          }
          oldHead = waiters; // re-read and loop.
        } while (oldHead != Waiter.TOMBSTONE);
      }

   *
   * @since 2.0
   */
  public abstract static class SetView<E extends @Nullable Object> extends AbstractSet<E> {
    private SetView() {} // no subclasses but our own

    /**
     * Returns an immutable copy of the current contents of this set view. Does not support null
     * elements.
     *

   * String a3 = peekingIterator.next(); // also returns "a"
   * }</pre>
   *
   * <p>Any structural changes to the underlying iteration (aside from those performed by the
   * iterator's own {@link PeekingIterator#remove()} method) will leave the iterator in an undefined
   * state.
   *
   * <p>The returned iterator does not support removal after peeking, as explained by {@link
   * PeekingIterator#remove()}.

   * @throws IllegalStateException if the {@code Future} is not done
   * @since 20.0
   */
  @CanIgnoreReturnValue
  // TODO(cpovirk): Consider calling getDone() in our own code.
  @ParametricNullness
  public static <V extends @Nullable Object> V getDone(Future<V> future) throws ExecutionException {
    /*

   * the map are reflected in the multimap, and vice versa. If the map is modified while an
   * iteration over one of the multimap's collection views is in progress (except through the
   * iterator's own {@code remove} operation, or through the {@code setValue} operation on a map
   * entry returned by the iterator), the results of the iteration are undefined.
   *