@CollectionFeature.Require({SUPPORTS_REMOVE, ALLOWS_NULL_VALUES})
  public void testRemove_nullPresent() {
    initCollectionWithNullElement();
    assertEquals(1, getMultiset().remove(null, 2));
    assertFalse(
        "multiset contains present after multiset.remove(present, 2)",
        getMultiset().contains(null));
    assertEquals(0, getMultiset().count(null));
  }

   * ParametricNullness parametric nullness}. Sometimes, code may receive a null {@code T} but store
   * a "null sentinel" to take its place. When the time comes to convert it back to a {@code T} to
   * return to a caller, the code needs to a way to return {@code null} from a method that returns
   * "plain {@code T}." This API provides that.
   */
  @SuppressWarnings({"nullness", "TypeParameterUnusedInFormals", "ReturnMissingNullable"})

        @javax.annotation.CheckForNull String s) {
      // null?  no problem
    }

    public static void staticOneArgJsr305NullableCorrectlyDoesNotThrowNPE(
        @javax.annotation.Nullable String s) {
      // null?  no problem
    }

    public static void staticOneArgNullableCorrectlyDoesNotThrowNPE(@Nullable String s) {
      // null?  no problem
    }

    } catch (RuntimeException tolerated) {
      // GWT's HashMap.entrySet().removeAll(null) doesn't throws NPE.
    }
  }

  @Override
  public void testEntrySetRetainAllNullFromEmpty() {
    try {
      super.testEntrySetRetainAllNullFromEmpty();
    } catch (RuntimeException tolerated) {
      // GWT's HashMap.entrySet().retainAll(null) doesn't throws NPE.
    }
  }

  @Override

    // Populate the results list with null initially.
    for (int i = 0; i < futures.size(); ++i) {
      values.add(null);
    }

    this.values = values;
  }

  @Override
  final void collectOneValue(int index, @ParametricNullness V returnValue) {
    List<@Nullable Present<V>> localValues = values;
    if (localValues != null) {
      localValues.set(index, new Present<>(returnValue));
    }

          }
        },
        "HashMap w/out null keys",
        ALLOWS_NULL_VALUES);
  }

  private static Test testsForHashMapNullValuesForbidden() {
    return wrappedHashMapTests(
        new WrappedHashMapGenerator() {
          @Override
          Map<String, String> wrap(final HashMap<String, String> map) {
            if (map.containsValue(null)) {
              throw new NullPointerException();

  }

  @CollectionFeature.Require(
      value = {SUPPORTS_ADD, ALLOWS_NULL_VALUES},
      absent = RESTRICTS_ELEMENTS)
  public void testAddAll_nullSupported() {
    List<E> containsNull = singletonList(null);
    assertTrue("addAll(containsNull) should return true", collection.addAll(containsNull));
    /*
     * We need (E) to force interpretation of null as the single element of a
     * varargs array, not the array itself
     */

    }
  }

  @MapFeature.Require({SUPPORTS_PUT, ALLOWS_NULL_VALUES})
  @CollectionSize.Require(absent = ZERO)
  public void testSetValueNullSupported() {
    for (Entry<K, V> entry : getMap().entrySet()) {
      if (entry.getKey().equals(k0())) {
        entry.setValue(null);
      }
    }
    expectReplacement(entry(k0(), (V) null));
  }

  @CollectionSize.Require(absent = ZERO)
  @MapFeature.Require(ALLOWS_NULL_KEYS)
  public void testKeySetContainsNullKeyPresent() {
    initMultimapWithNullKey();
    assertTrue(multimap().keySet().contains(null));
  }

  @MapFeature.Require(ALLOWS_NULL_KEY_QUERIES)
  public void testKeySetContainsNullKeyAbsent() {
    assertFalse(multimap().keySet().contains(null));
  }

  @MapFeature.Require(SUPPORTS_REMOVE)

     */
    if (result == null) {
      return null;
    } else {
      return (V) result;
    }
  }

  @CheckForNull
  static Object get(
      @CheckForNull Object hashTableObject,
      @Nullable Object[] alternatingKeysAndValues,
      int size,
      int keyOffset,
      @CheckForNull Object key) {
    if (key == null) {
      return null;
    } else if (size == 1) {