* @throws NullPointerException if both {@code first} and {@code second} are null
   * @since 18.0 (since 3.0 as {@code Objects.firstNonNull()}).
   */
  public static <T> T firstNonNull(@Nullable T first, @Nullable T second) {
    if (first != null) {
      return first;
    }
    if (second != null) {
      return second;
    }
    throw new NullPointerException("Both parameters are null");
  }

  /**

     *
     * <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);

    /**

    Boolean b1 = true;
    Boolean b2 = MoreObjects.firstNonNull(b1, null);
    assertSame(b1, b2);
  }

  public void testFirstNonNull_throwsNullPointerException() {
    assertThrows(NullPointerException.class, () -> MoreObjects.firstNonNull(null, null));
  }

  // ToStringHelper's tests are in ToStringHelperTest

  @J2ktIncompatible
  @GwtIncompatible("NullPointerTester")

    Boolean b1 = true;
    Boolean b2 = MoreObjects.firstNonNull(b1, null);
    assertSame(b1, b2);
  }

  public void testFirstNonNull_throwsNullPointerException() {
    assertThrows(NullPointerException.class, () -> MoreObjects.firstNonNull(null, null));
  }

  // ToStringHelper's tests are in ToStringHelperTest

  @J2ktIncompatible
  @GwtIncompatible("NullPointerTester")

    }

    /**
     * Associates all of the given map's keys and values in the built bimap. Duplicate keys or
     * values are not allowed, and will cause {@link #build} to fail.
     *
     * @throws NullPointerException if any key or value in {@code map} is null
     */
    @CanIgnoreReturnValue
    @Override
    public Builder<K, V> putAll(Map<? extends K, ? extends V> map) {
      super.putAll(map);
      return this;

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

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

        new WrappedHashMapGenerator() {
          @Override
          Map<String, String> wrap(HashMap<String, String> map) {
            if (map.containsKey(null)) {
              throw new NullPointerException();
            }
            return new AbstractMap<String, String>() {
              @Override
              public Set<Entry<String, String>> entrySet() {
                return map.entrySet();

  }

  @CollectionFeature.Require(absent = ALLOWS_NULL_QUERIES)
  public void testContainsAll_nullNotAllowed() {
    try {
      assertFalse(collection.containsAll(MinimalCollection.of((E) null)));
    } catch (NullPointerException tolerated) {
    }
  }

  @CollectionFeature.Require(ALLOWS_NULL_QUERIES)
  public void testContainsAll_nullAllowed() {
    assertFalse(collection.containsAll(MinimalCollection.of((E) null)));
  }

    assertEquals("multiset.count(null) didn't return 0", 0, getMultiset().count(null));
  }

  @CollectionFeature.Require(absent = ALLOWS_NULL_QUERIES)
  public void testCount_null_forbidden() {
    assertThrows(NullPointerException.class, () -> getMultiset().count(null));
  }

  @CollectionSize.Require(absent = ZERO)
  @CollectionFeature.Require(ALLOWS_NULL_VALUES)
  public void testCount_nullPresent() {
    initCollectionWithNullElement();

    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);