Set<Object> absentAsSet = Optional.absent().asSet();
    try {
      absentAsSet.add("foo");
      fail();
    } catch (UnsupportedOperationException expected) {
    }
  }

  public void testTransform_absent() {
    assertEquals(Optional.absent(), Optional.absent().transform(Functions.identity()));
    assertEquals(Optional.absent(), Optional.absent().transform(Functions.toStringFunction()));
  }

    expectUnchanged();
  }

  @CollectionFeature.Require(absent = SUPPORTS_REMOVE)
  @CollectionSize.Require(ZERO)
  public void testRetainAll_emptyPreviouslyEmptyUnsupported() {
    expectReturnsFalseOrThrows(empty);
    expectUnchanged();
  }

  @CollectionFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(absent = ZERO)
  public void testRetainAll_emptyPreviouslyNonEmpty() {

  }

  @CollectionSize.Require(absent = ZERO)
  public void testHeadMapExclusive() {
    assertFalse(navigableMap.headMap(a.getKey(), false).containsKey(a.getKey()));
  }

  @CollectionSize.Require(absent = ZERO)
  public void testHeadMapInclusive() {
    assertTrue(navigableMap.headMap(a.getKey(), true).containsKey(a.getKey()));
  }

  @CollectionSize.Require(absent = ZERO)
  public void testTailMapExclusive() {

  @CollectionFeature.Require(SUPPORTS_ADD)
  @CollectionSize.Require(absent = ZERO)
  public void testAdd_supportedPresent() {
    assertTrue("add(present) should return true", getList().add(e0()));
    expectAdded(e0());
  }

  @CollectionFeature.Require(absent = SUPPORTS_ADD)
  @CollectionSize.Require(absent = ZERO)
  /*
   * absent = ZERO isn't required, since unmodList.add() must

@ElementTypesAreNonnullByDefault
public class MultimapPutTester<K extends @Nullable Object, V extends @Nullable Object>
    extends AbstractMultimapTester<K, V, Multimap<K, V>> {
  @MapFeature.Require(absent = SUPPORTS_PUT)
  public void testPutUnsupported() {
    try {
      multimap().put(k3(), v3());
      fail("Expected UnsupportedOperationException");
    } catch (UnsupportedOperationException expected) {
    }
  }

  }

  @CollectionFeature.Require(absent = SUPPORTS_ADD)
  public void testAdd_unsupportedNotPresent() {
    try {
      collection.add(e3());
      fail("add(notPresent) should throw");
    } catch (UnsupportedOperationException expected) {
    }
    expectUnchanged();
    expectMissing(e3());
  }

  @CollectionFeature.Require(absent = SUPPORTS_ADD)
  @CollectionSize.Require(absent = ZERO)

  }

  @CollectionFeature.Require(value = KNOWN_ORDER, absent = SUPPORTS_ITERATOR_REMOVE)
  public void testIterator_knownOrderRemoveUnsupported() {
    runIteratorTest(UNMODIFIABLE, IteratorTester.KnownOrder.KNOWN_ORDER, getOrderedElements());
  }

  @CollectionFeature.Require(absent = KNOWN_ORDER, value = SUPPORTS_ITERATOR_REMOVE)
  public void testIterator_unknownOrderRemoveSupported() {

  @CollectionSize.Require(absent = ZERO)
  public void testAddAllAtIndex_supportedAllPresent() {
    assertTrue(
        "addAll(n, allPresent) should return true",
        getList().addAll(0, MinimalCollection.of(e0())));
    expectAdded(0, e0());
  }

  @ListFeature.Require(absent = SUPPORTS_ADD_WITH_INDEX)
  @CollectionSize.Require(absent = ZERO)
  public void testAddAllAtIndex_unsupportedAllPresent() {

  }

  @CollectionSize.Require(ZERO)
  public void testIsEmptyYes() {
    assertTrue(multimap().isEmpty());
  }

  @CollectionSize.Require(absent = ZERO)
  public void testIsEmptyNo() {
    assertFalse(multimap().isEmpty());
  }

  @CollectionSize.Require(absent = ZERO)
  @MapFeature.Require(ALLOWS_NULL_KEYS)
  public void testSizeNullKey() {
    initMultimapWithNullKey();

  }

  @CollectionSize.Require(ZERO)
  public void testIsEmptyYes() {
    assertTrue(multimap().isEmpty());
  }

  @CollectionSize.Require(absent = ZERO)
  public void testIsEmptyNo() {
    assertFalse(multimap().isEmpty());
  }

  @CollectionSize.Require(absent = ZERO)
  @MapFeature.Require(ALLOWS_NULL_KEYS)
  public void testSizeNullKey() {
    initMultimapWithNullKey();