*/
@SuppressWarnings("rawtypes") // maybe avoidable if we rework the whole package?
@GwtCompatible
public enum CollectionFeature implements Feature<Collection> {
  /**
   * The collection must not throw {@code NullPointerException} on calls such as {@code
   * contains(null)} or {@code remove(null)}, but instead must return a simple {@code false}.
   */
  ALLOWS_NULL_QUERIES,
  ALLOWS_NULL_VALUES(ALLOWS_NULL_QUERIES),

  /**

    assertFalse(multimap().containsKey(null));
  }

  @MapFeature.Require(absent = ALLOWS_NULL_KEY_QUERIES)
  public void testContainsKeyNullDisallowed() {
    assertThrows(NullPointerException.class, () -> multimap().containsKey(null));
  }

  @CollectionSize.Require(absent = ZERO)
  public void testCreateWithNull_unsupported() {
    E[] array = createArrayWithNullElement();

    assertThrows(
        NullPointerException.class,
        () -> {
          Object unused = getSubjectGenerator().create(array);
        });
  }

  /**
   * Returns the {@link Method} instance for {@link #testCreateWithNull_unsupported()} so that tests

  @CollectionSize.Require(absent = ZERO)
  public void testSetValueNullUnsupported() {
    for (Entry<K, V> entry : getMap().entrySet()) {
      assertThrows(NullPointerException.class, () -> entry.setValue(null));
      expectUnchanged();
    }
  }

  @MapFeature.Require({SUPPORTS_PUT, ALLOWS_NULL_VALUES})
  @CollectionSize.Require(absent = ZERO)

  @CollectionSize.Require(absent = ZERO)
  public void testCreateWithNull_unsupported() {
    E[] array = createArrayWithNullElement();

    assertThrows(
        NullPointerException.class,
        () -> {
          Object unused = getSubjectGenerator().create(array);
        });
  }

  /**
   * Returns the {@link Method} instance for {@link #testCreateWithNull_unsupported()} so that tests

    assertSetCount(null, 1);
  }

  @CollectionFeature.Require(value = SUPPORTS_ADD, absent = ALLOWS_NULL_VALUES)
  public void testSetCount_addNull_nullUnsupported() {
    assertThrows(NullPointerException.class, () -> setCountNoCheckReturnValue(null, 1));
  }

  @CollectionFeature.Require(ALLOWS_NULL_VALUES)
  public void testSetCount_noOpNull_nullSupported() {
    try {
      assertSetCount(null, 0);

  }

  @MapFeature.Require(absent = ALLOWS_NULL_KEY_QUERIES)
  public void testGet_nullNotContainedAndUnsupported() {
    try {
      assertNull("get(null) should return null or throw", get(null));
    } catch (NullPointerException tolerated) {
    }
  }

  @MapFeature.Require(ALLOWS_NULL_KEYS)
  @CollectionSize.Require(absent = ZERO)
  public void testGet_nonNullWhenNullContained() {
    initMapWithNullKey();

   * null} treated as {@link #absent}, use {@link #fromNullable} instead.
   *
   * <p><b>Comparison to {@code java.util.Optional}:</b> no differences.
   *
   * @throws NullPointerException if {@code reference} is null
   */
  public static <T> Optional<T> of(T reference) {
    return new Present<>(checkNotNull(reference));
  }

  /**

            return "RAW";
          }
        };
    try {
      Hashing.hmacMd5(badKey);
      fail();
    } catch (IllegalArgumentException expected) {
    } catch (NullPointerException toleratedOnAndroid) {
      // TODO(cpovirk): In an ideal world, we'd check here that we're running on Android.
    }
  }

  public void testEmptyInputs() throws Exception {

    expectAdded(0, (E) null);
  }

  @ListFeature.Require(SUPPORTS_ADD_WITH_INDEX)
  @CollectionFeature.Require(absent = ALLOWS_NULL_VALUES)
  public void testAddAtIndex_nullUnsupported() {
    assertThrows(NullPointerException.class, () -> getList().add(0, null));
    expectUnchanged();
    expectNullMissingWhenNullUnsupported("Should not contain null after unsupported add(n, null)");
  }

  @ListFeature.Require(SUPPORTS_ADD_WITH_INDEX)