*       captured by any of the steps in the pipeline are closed.
 * </ol>
 *
 * <h3>Starting a pipeline</h3>
 *
 * Start a {@code ClosingFuture} pipeline {@linkplain #submit(ClosingCallable, Executor) from a
 * callable block} that may capture objects for later closing. To start a pipeline from a {@link
 * ListenableFuture} that doesn't create resources that should be closed later, you can use {@link

              return key + "Load";
            }

            @Override
            public ListenableFuture<String> reload(String key, String oldValue) {
              return refreshExecutor.submit(
                  () -> {
                    reloadStarted.countDown();

                    Thread blockingForRefresh = threadAboutToBlockForRefresh.get();
                    while (blockingForRefresh.isAlive()

              return key + "Load";
            }

            @Override
            public ListenableFuture<String> reload(String key, String oldValue) {
              return refreshExecutor.submit(
                  () -> {
                    reloadStarted.countDown();

                    Thread blockingForRefresh = threadAboutToBlockForRefresh.get();
                    while (blockingForRefresh.isAlive()

      }

      @Override
      public SortedSet<E> subSet(
          @ParametricNullness E fromElement, @ParametricNullness E toElement) {
        return removeOnlySortedSet(super.subSet(fromElement, toElement));
      }

      @Override
      public NavigableSet<E> subSet(
          @ParametricNullness E fromElement,
          boolean fromInclusive,