List<@Nullable Integer> values = Arrays.asList(1, null);
    assertThrows(
        NullPointerException.class,
        () -> Multimaps.index((List<Integer>) values, Functions.identity()));
  }

  public void testIndex_nullKey() {
    List<Integer> values = Arrays.asList(1, 2);
    assertThrows(
        NullPointerException.class, () -> Multimaps.index(values, Functions.constant(null)));
  }

      AvlNode<E> root = rootReference.get();
      if (!range.contains(e) || root == null) {
        return 0;
      }
      return root.count(comparator(), e);
    } catch (ClassCastException | NullPointerException e) {
      return 0;
    }
  }

  @CanIgnoreReturnValue
  @Override
  public int add(@ParametricNullness E element, int occurrences) {
    checkNonnegative(occurrences, "occurrences");

    @Override
    public OutputStream openStream() {
      return ByteStreams.nullOutputStream();
    }
  }

  // Compare by toString() to satisfy 2 properties:
  // 1. compareTo(null) should throw NullPointerException
  // 2. the order is deterministic and easy to understand, for debugging purpose.
  @SuppressWarnings("ComparableType")
  private static final class ByToString implements Comparable<Object>, Serializable {

     *         obtained, the returned version range's recommended version is set to <code>null</code>.
     *         </p>
     * @throws NullPointerException if the specified <code>VersionRange</code> is
     *                              <code>null</code>.
     */
    public VersionRange restrict(VersionRange restriction) {

        }
      }
    }
  }

  public void testToArray_withNull() {
    List<@Nullable Character> list = Arrays.asList((char) 0, (char) 1, null);
    assertThrows(NullPointerException.class, () -> Chars.toArray(list));
  }

  @J2ktIncompatible // b/285319375
  public void testAsList_isAView() {
    char[] array = {(char) 0, (char) 1};
    List<Character> list = Chars.asList(array);

   * necessary.
   *
   * <p>The returned iterator supports {@code remove()} when the corresponding input iterator
   * supports it.
   *
   * @throws NullPointerException if any of the provided iterators is null
   */
  @SafeVarargs
  public static <T extends @Nullable Object> Iterator<T> concat(Iterator<? extends T>... inputs) {

    // https://android-review.googlesource.com/#/c/271775/
    try {
      source = rawSocket.source().buffer()
      sink = rawSocket.sink().buffer()
    } catch (npe: NullPointerException) {
      if (npe.message == NPE_THROW_WITH_NULL) {
        throw IOException(npe)
      }
    }
  }

  /**

    assertTrue(toTest, toTest.matches(expectedRegex));
  }

  public void testToString_addWithNullName() {
    MoreObjects.ToStringHelper helper = MoreObjects.toStringHelper(new TestClass());
    assertThrows(NullPointerException.class, () -> helper.add(null, "Hello"));
  }

  @GwtIncompatible // Class names are obfuscated in GWT
  public void testToString_addWithNullValue() {

    Predicate<Class<?>> isInteger = Predicates.subtypeOf(Integer.class);

    assertTrue(isInteger.apply(Integer.class));
    assertFalse(isInteger.apply(Float.class));

    assertThrows(NullPointerException.class, () -> isInteger.apply(null));
  }

  @J2ktIncompatible
  @GwtIncompatible // Predicates.subtypeOf
  public void testSubtypeOf_subclass() {

   * We don't permit nulls, but we wrap every comparator with nullsFirst().
   * Why? We want for queries like containsKey(null) to return false, but the
   * GWT SortedMap implementation that we delegate to throws
   * NullPointerException if the comparator does. Since our construction
   * methods ensure that null is never present in the map, it's OK for the
   * comparator to look for it wherever it wants.
   *