@MapFeature.Require(SUPPORTS_PUT)
  public void testPutAll_supportedNonePresent() {
    putAll(createDisjointCollection());
    expectAdded(e3(), e4());
  }

  @MapFeature.Require(absent = SUPPORTS_PUT)
  public void testPutAll_unsupportedNonePresent() {
    assertThrows(UnsupportedOperationException.class, () -> putAll(createDisjointCollection()));
    expectUnchanged();
    expectMissing(e3(), e4());
  }

    assertTrue(
        "addAll(nonePresent) should return true", collection.addAll(createDisjointCollection()));
    expectAdded(e3(), e4());
  }

  @CollectionFeature.Require(absent = SUPPORTS_ADD)
  public void testAddAll_unsupportedNonePresent() {
    assertThrows(
        UnsupportedOperationException.class, () -> collection.addAll(createDisjointCollection()));
    expectUnchanged();
    expectMissing(e3(), e4());
  }

  @MapFeature.Require(SUPPORTS_PUT)
  public void testPutAll_supportedNonePresent() {
    putAll(createDisjointCollection());
    expectAdded(e3(), e4());
  }

  @MapFeature.Require(absent = SUPPORTS_PUT)
  public void testPutAll_unsupportedNonePresent() {
    assertThrows(UnsupportedOperationException.class, () -> putAll(createDisjointCollection()));
    expectUnchanged();
    expectMissing(e3(), e4());
  }

      assertFalse(message, getMap().containsValue(null));
    } catch (NullPointerException tolerated) {
      // Tolerated
    }
  }

  @Override
  protected MinimalCollection<Entry<K, V>> createDisjointCollection() {
    return MinimalCollection.of(e3(), e4());
  }

  protected int getNumEntries() {
    return getNumElements();
  }

  protected Collection<Entry<K, V>> getSampleEntries(int howMany) {

      assertFalse(message, getMap().containsValue(null));
    } catch (NullPointerException tolerated) {
      // Tolerated
    }
  }

  @Override
  protected MinimalCollection<Entry<K, V>> createDisjointCollection() {
    return MinimalCollection.of(e3(), e4());
  }

  protected int getNumEntries() {
    return getNumElements();
  }

  protected Collection<Entry<K, V>> getSampleEntries(int howMany) {

   *     that involve a null element being present.
   */
  protected int getNullLocation() {
    return getNumElements() / 2;
  }

  protected MinimalCollection<E> createDisjointCollection() {
    return MinimalCollection.of(e3(), e4());
  }

  protected MinimalCollection<E> emptyCollection() {
    return MinimalCollection.of();
  }

  protected final E e0() {