}

  @CollectionFeature.Require(absent = SUPPORTS_ADD)
  @CollectionSize.Require(absent = ZERO)
  public void testAddAll_unsupportedSomePresent() {
    assertThrows(
        UnsupportedOperationException.class,
        () -> collection.addAll(MinimalCollection.of(e3(), e0())));
    expectUnchanged();
  }

  @CollectionFeature.Require({SUPPORTS_ADD, FAILS_FAST_ON_CONCURRENT_MODIFICATION})

  }

  @CollectionSize.Require(absent = ZERO)
  @MapFeature.Require(ALLOWS_NULL_KEYS)
  public void testContainsEntryWithNullKeyPresent() {
    initMultimapWithNullKey();
    assertContains(multimap().entries(), mapEntry((K) null, getValueForNullKey()));
  }

  @MapFeature.Require(ALLOWS_NULL_KEY_QUERIES)
  public void testContainsEntryWithNullKeyAbsent() {

  }

  @MapFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(absent = ZERO)
  public void testClearPropagatesToGet() {
    for (K key : sampleKeys()) {
      resetContainer();
      Collection<V> collection = multimap().get(key);
      multimap().clear();
      assertEmpty(collection);
    }
  }

  @MapFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(absent = ZERO)

                (k, v) -> {
                  throw new AssertionFailedError();
                }));
    expectUnchanged();
  }

  @MapFeature.Require(SUPPORTS_PUT)
  @CollectionSize.Require(absent = ZERO)
  public void testComputeIfPresent_supportedPresent() {
    assertEquals(
        "computeIfPresent(present, function) should return new value",
        v3(),
        getMap()
            .computeIfPresent(
                k0(),

          iterator.next();
        });
  }

  @CollectionFeature.Require(SUPPORTS_REMOVE)
  public void testRemove_notPresent() {
    assertFalse("remove(notPresent) should return false", collection.remove(e3()));
    expectUnchanged();
  }

  @CollectionFeature.Require({SUPPORTS_REMOVE, ALLOWS_NULL_VALUES})
  @CollectionSize.Require(absent = ZERO)
  public void testRemove_nullPresent() {

  @ListFeature.Require(SUPPORTS_REMOVE_WITH_INDEX)
  @CollectionSize.Require(absent = {ZERO, ONE})
  public void testRemoveAtIndex_middle() {
    runRemoveTest(getNumElements() / 2);
  }

  @CollectionFeature.Require(FAILS_FAST_ON_CONCURRENT_MODIFICATION)
  @ListFeature.Require(SUPPORTS_REMOVE_WITH_INDEX)
  @CollectionSize.Require(absent = ZERO)
  public void testRemoveAtIndexConcurrentWithIteration() {
    assertThrows(

                k3(),
                k -> {
                  assertEquals(k3(), k);
                  return v3();
                }));
    expectAdded(e3());
  }

  @MapFeature.Require(SUPPORTS_PUT)
  @CollectionSize.Require(absent = ZERO)
  public void testComputeIfAbsent_supportedPresent() {
    assertEquals(
        "computeIfAbsent(present, function) should return existing value",
        v0(),
        getMap()

  }

  @CollectionSize.Require(absent = ZERO)
  @CollectionFeature.Require(absent = NON_STANDARD_TOSTRING)
  @MapFeature.Require(ALLOWS_NULL_KEYS)
  public void testToStringWithNullKey() {
    initMapWithNullKey();
    testToString_formatting();
  }

  @CollectionSize.Require(absent = ZERO)
  @CollectionFeature.Require(absent = NON_STANDARD_TOSTRING)
  @MapFeature.Require(ALLOWS_NULL_VALUES)

    return (ConcurrentMap<K, V>) super.getMap();
  }

  @MapFeature.Require(SUPPORTS_PUT)
  public void testPutIfAbsent_supportedAbsent() {
    assertNull("putIfAbsent(notPresent, value) should return null", putIfAbsent(e3()));
    expectAdded(e3());
  }

  @MapFeature.Require(SUPPORTS_PUT)
  @CollectionSize.Require(absent = ZERO)
  public void testPutIfAbsent_supportedPresent() {
    assertEquals(

                  throw new AssertionFailedError(
                      "Should not call merge function if key was absent");
                }));
    expectAdded(e3());
  }

  @MapFeature.Require({SUPPORTS_PUT, ALLOWS_NULL_VALUES})
  @CollectionSize.Require(absent = ZERO)
  public void testMappedToNull() {
    initMapWithNullValue();
    assertEquals(
        "Map.merge(keyMappedToNull, value, function) should return value",
        v3(),