*
   * @throws NullPointerException if the element is null
   */
  public static <E> ImmutableList<E> of(E e1) {
    return new SingletonImmutableList<>(e1);
  }

  /**
   * Returns an immutable list containing the given elements, in order.
   *
   * @throws NullPointerException if any element is null
   */
  public static <E> ImmutableList<E> of(E e1, E e2) {

   * When multiple elements are equivalent according to {@link Comparable#compareTo}, only the first
   * one specified is included.
   *
   * @throws NullPointerException if any element is null
   */
  public static <E extends Comparable<? super E>> ImmutableSortedSet<E> of(E e1, E e2) {
    return construct(Ordering.natural(), 2, e1, e2);
  }

  /**

   *
   * @throws NullPointerException if any element is null
   */
  public static <E extends Comparable<? super E>> ImmutableSortedMultiset<E> of(
      E e1, E e2, E e3, E e4) {
    return copyOf(Ordering.natural(), Arrays.asList(e1, e2, e3, e4));
  }

  /**
   * Returns an immutable sorted multiset containing the given elements sorted by their natural
   * ordering.
   *
   * @throws NullPointerException if any element is null

    ImmutableMultiset.Builder<String> builder = ImmutableMultiset.builder();
    assertThrows(NullPointerException.class, () -> builder.add((String) null));
  }

  public void testBuilderAddAllHandlesNullsCorrectly() {
    {
      ImmutableMultiset.Builder<String> builder = ImmutableMultiset.builder();
      assertThrows(NullPointerException.class, () -> builder.addAll((Collection<String>) null));
    }

    {

              });
      fail("Expected NullPointerException or UnsupportedOperationException");
    } catch (NullPointerException | UnsupportedOperationException expected) {
    }
  }

  public void testMergeNullFunction() {
    try {
      getMap().merge(k0(), v3(), null);
      fail("Expected NullPointerException or UnsupportedOperationException");
    } catch (NullPointerException | UnsupportedOperationException expected) {

              });
      fail("Expected NullPointerException or UnsupportedOperationException");
    } catch (NullPointerException | UnsupportedOperationException expected) {
    }
  }

  public void testMergeNullFunction() {
    try {
      getMap().merge(k0(), v3(), null);
      fail("Expected NullPointerException or UnsupportedOperationException");
    } catch (NullPointerException | UnsupportedOperationException expected) {

public enum MapFeature implements Feature<Map> {
  /**
   * The map does not throw {@code NullPointerException} on calls such as {@code containsKey(null)},
   * {@code get(null)}, {@code keySet().contains(null)} or {@code remove(null)}.
   */
  ALLOWS_NULL_KEY_QUERIES,
  ALLOWS_NULL_KEYS(ALLOWS_NULL_KEY_QUERIES),
  /**
   * The map does not throw {@code NullPointerException} on calls such as {@code

   * @return the non-null reference that was validated
   * @throws NullPointerException if {@code reference} is null
   * @see Verify#verifyNotNull Verify.verifyNotNull()
   */
  @CanIgnoreReturnValue
  public static <T> T checkNotNull(@Nullable T reference) {
    if (reference == null) {
      throw new NullPointerException();
    }
    return reference;
  }

  /**

    Set<Entry<K, V>> entrySet = map.entrySet();
    if (supportsRemove) {
      assertThrows(NullPointerException.class, () -> entrySet.removeAll(null));
    } else {
      try {
        entrySet.removeAll(null);
        fail("Expected UnsupportedOperationException or NullPointerException.");
      } catch (UnsupportedOperationException | NullPointerException e) {
        // Expected.
      }
    }
    assertInvariants(map);
  }

     * @param useDefaultExcludes whether to augment excludes with default SCM exclusion patterns
     * @return a PathMatcher that can be used to test if paths should be included
     * @throws NullPointerException if baseDirectory is null
     */
    @Nonnull
    PathMatcher createPathMatcher(
            @Nonnull Path baseDirectory,
            Collection<String> includes,
            Collection<String> excludes,