NavigableSet<Integer> filtered = filter(createUnfiltered(contents), EVEN);
        NavigableSet<Integer> unfiltered = createUnfiltered(filtered);

        assertThat(filtered.descendingSet())
            .containsExactlyElementsIn(unfiltered.descendingSet())
            .inOrder();
      }
    }

    public void testPollFirst() {
      for (List<Integer> contents : SAMPLE_INPUTS) {

              @Override
              public Set<E> create(Object... elements) {
                NavigableSet<E> navigableSet = (NavigableSet<E>) delegate.create(elements);
                return navigableSet.descendingSet();
              }
            })
        .named(parentBuilder.getName() + " descending")
        .withFeatures(features)
        .suppressing(parentBuilder.getSuppressedTests())
        .createTestSuite();

  transient @Nullable ImmutableSortedSet<E> descendingSet;

  /**
   * @since 12.0
   */
  @GwtIncompatible // NavigableSet
  @Override
  public ImmutableSortedSet<E> descendingSet() {
    // racy single-check idiom
    ImmutableSortedSet<E> result = descendingSet;
    if (result == null) {
      result = descendingSet = createDescendingSet();
      result.descendingSet = this;
    }
    return result;
  }

              @Override
              public Set<E> create(Object... elements) {
                NavigableSet<E> navigableSet = (NavigableSet<E>) delegate.create(elements);
                return navigableSet.descendingSet();
              }
            })
        .named(parentBuilder.getName() + " descending")
        .withFeatures(features)
        .suppressing(parentBuilder.getSuppressedTests())
        .createTestSuite();

      return new WrappedNavigableSet(key, wrapped, (getAncestor() == null) ? this : getAncestor());
    }

    @Override
    public NavigableSet<V> descendingSet() {
      return wrap(getSortedSetDelegate().descendingSet());
    }

    @Override
    public Iterator<V> descendingIterator() {
      return new WrappedIterator(getSortedSetDelegate().descendingIterator());
    }

    @Override

    NavigableSet<E> empty = navigableSet.subSet(e0(), false, e0(), false);
    assertEquals(new TreeSet<E>(), empty);
  }

  /*
   * TODO(cpovirk): more testing of subSet/headSet/tailSet/descendingSet? and/or generate derived
   * suites?
   */

  /**
   * Returns the {@link Method} instances for the test methods in this class that create a set with

    NavigableSet<E> empty = navigableSet.subSet(e0(), false, e0(), false);
    assertEquals(new TreeSet<E>(), empty);
  }

  /*
   * TODO(cpovirk): more testing of subSet/headSet/tailSet/descendingSet? and/or generate derived
   * suites?
   */

  /**
   * Returns the {@link Method} instances for the test methods in this class that create a set with

    /* Unmodifiable is a view. */
    mod.add(4);
    assertTrue(unmod.contains(4));
    assertTrue(unmod.descendingSet().contains(4));

    ensureNotDirectlyModifiable(unmod);
    ensureNotDirectlyModifiable(unmod.descendingSet());
    ensureNotDirectlyModifiable(unmod.headSet(2));
    ensureNotDirectlyModifiable(unmod.headSet(2, true));

              .createTestSuite());

      suite.addTest(
          NavigableSetTestSuiteBuilder.using(new ContiguousSetDescendingGenerator())
              .named("Range.asSet.descendingSet")
              .withFeatures(
                  CollectionSize.ANY,
                  KNOWN_ORDER,
                  ALLOWS_NULL_QUERIES,
                  NON_STANDARD_TOSTRING,

              .createTestSuite());

      suite.addTest(
          NavigableSetTestSuiteBuilder.using(new ContiguousSetDescendingGenerator())
              .named("Range.asSet.descendingSet")
              .withFeatures(
                  CollectionSize.ANY,
                  KNOWN_ORDER,
                  ALLOWS_NULL_QUERIES,
                  NON_STANDARD_TOSTRING,