}

  // This test assumes that the implementation does not support null keys.
  public void testRowNull() {
    table = create("foo", 1, 'a', "bar", 1, 'b', "foo", 3, 'c');
    assertThrows(NullPointerException.class, () -> table.row(null));
  }

  public void testColumn() {
    table = create("foo", 1, 'a', "bar", 1, 'b', "foo", 3, 'c');
    assertEquals(ImmutableMap.of("foo", 'a', "bar", 'b'), table.column(1));

   * 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));
  }

  /**

   * @throws IllegalArgumentException if {@code occurrences} is negative, or if this operation would
   *     result in more than {@link Integer#MAX_VALUE} occurrences of the element
   * @throws NullPointerException if {@code element} is null and this implementation does not permit
   *     null elements. Note that if {@code occurrences} is zero, the implementation may opt to
   *     return normally.
   */
  @CanIgnoreReturnValue

  public void testContainsNullValueNo() {
    assertFalse(multimap().containsValue(null));
  }

  @MapFeature.Require(absent = ALLOWS_NULL_VALUE_QUERIES)
  public void testContainsNullValueFails() {
    assertThrows(NullPointerException.class, () -> multimap().containsValue(null));
  }

    try {
      assertEquals(
          "getOrDefault(null, def) should return default or throw",
          v3(),
          getMap().getOrDefault(null, v3()));
    } catch (NullPointerException tolerated) {
    }
  }

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

    }

    /**
     * Associates all of {@code map's} keys and values in the built map. Duplicate keys are not
     * allowed, and will cause {@link #build} to fail.
     *
     * @throws NullPointerException if any key or value in {@code map} is null
     * @throws ClassCastException if any value is not an instance of the type specified by its key
     */
    @CanIgnoreReturnValue

     *
     * <p>Note that each builder class covariantly returns its own type from this method.
     *
     * @param element the element to add
     * @return this {@code Builder} instance
     * @throws NullPointerException if {@code element} is null
     */
    @CanIgnoreReturnValue
    public abstract Builder<E> add(E element);

    /**

    }
    assertThrows(IndexOutOfBoundsException.class, () -> refArray.get(array.length));
  }

  public void testNewReferenceArray_withNullArray() throws Exception {
    assertThrows(NullPointerException.class, () -> Atomics.newReferenceArray(null));
  }

  public void testNullPointers() {
    NullPointerTester tester = new NullPointerTester();
    tester.testAllPublicConstructors(Atomics.class); // there aren't any

    expectAdded((E) null);
  }

  @CollectionFeature.Require(value = SUPPORTS_ADD, absent = ALLOWS_NULL_VALUES)
  public void testOffer_nullUnsupported() {
    assertThrows(NullPointerException.class, () -> getQueue().offer(null));
    expectUnchanged();
    expectNullMissingWhenNullUnsupported("Should not contain null after unsupported offer(null)");
  }

    // Assert that escapers throw null pointer exceptions.
    try {
      escaper.escape((String) null);
      Assert.fail("exception not thrown when escaping a null string");
    } catch (NullPointerException e) {
      // pass
    }
  }

  /**
   * Asserts that an escaper escapes the given character into the expected string.
   *
   * @param escaper the non-null escaper to test