unfiltered.add("yyy");
                Collections.addAll(unfiltered, elements);
                unfiltered.add("zzz");
                return Sets.filter(unfiltered, Collections2Test.NOT_YYY_ZZZ);
              }
            })
        .named("Sets.filter")
        .withFeatures(
            CollectionFeature.SUPPORTS_ADD,

    assertEquals(Integer.valueOf(3), map.remove("two"));
    assertThat(strings).containsExactly("one", "three").inOrder();
    assertEquals(mapEntry("three", 5), map.subMap("one", false, "zzz", true).pollLastEntry());
    assertThat(strings).contains("one");
  }

  @GwtIncompatible // NavigableMap
  public void testAsMapNavigableSubViewKeySetsDoNotSupportAdd() {

    assertEquals(Integer.valueOf(3), map.remove("two"));
    assertThat(strings).containsExactly("one", "three").inOrder();
    assertEquals(mapEntry("three", 5), map.subMap("one", false, "zzz", true).pollLastEntry());
    assertThat(strings).contains("one");
  }

  @GwtIncompatible // NavigableMap
  public void testAsMapNavigableSubViewKeySetsDoNotSupportAdd() {