@CollectionSize.Require(SEVERAL)
  public void testLast() {
    assertEquals(c, navigableMap.lastEntry());
  }

  @MapFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(SEVERAL)
  public void testPollLast() {
    assertEquals(c, navigableMap.pollLastEntry());
    assertEquals(entries.subList(0, entries.size() - 1), copyToList(navigableMap.entrySet()));
  }

  @MapFeature.Require(absent = SUPPORTS_REMOVE)

        assertEquals(unfiltered.pollFirst(), filtered.pollFirst());
        assertEquals(unfiltered, filtered);
      }
    }

    public void testPollLast() {
      for (List<Integer> contents : SAMPLE_INPUTS) {
        NavigableSet<Integer> filtered = filter(createUnfiltered(contents), EVEN);
        NavigableSet<Integer> unfiltered = createUnfiltered(filtered);