*             impossible.
   *         <li>Test will fail if the constructor or factory method throws exception.
   *       </ul>
   *   <li>If there is no non-private constructor or non-private static factory method declared by
   *       {@code cls}, instance methods are skipped for nulls test.

    Predicate<@Nullable Integer> isNull = Predicates.equalTo(null);
    assertTrue(isNull.apply(null));
    assertFalse(isNull.apply(1));
  }

  public void testIsEqualToNull_equality() {
    new EqualsTester()
        .addEqualityGroup(
            Predicates.<@Nullable Integer>equalTo(null),
            Predicates.<@Nullable Integer>equalTo(null))
        .addEqualityGroup(Predicates.equalTo(1))

      for (Object element : contents) {
        if (element == null) {
          throw new NullPointerException();
        }
      }
    }
  }

  @Override
  public int size() {
    return contents.length;
  }

  @Override
  public boolean contains(@Nullable Object object) {
    if (!allowNulls) {
      // behave badly
      if (object == null) {
        throw new NullPointerException();
      }
    }

  }

  public void testCopyOf_map_nulls() {
    Map<Class<? extends Number>, Number> nullKey = Collections.singletonMap(null, (Number) 1.0);
    assertThrows(NullPointerException.class, () -> ImmutableClassToInstanceMap.copyOf(nullKey));

    Map<? extends Class<? extends Number>, Number> nullValue =
        Collections.singletonMap(Number.class, null);

    return asImmutableList(array);
  }

  /** Views the array as an immutable list. Checks for nulls; does not copy. */
  private static <E> ImmutableList<E> construct(Object... elements) {
    return asImmutableList(checkElementsNotNull(elements));
  }

  /**
   * Views the array as an immutable list. Does not check for nulls; does not copy.
   *
   * <p>The array must be internally created.
   */

       * we're copying into a `contents` array whose type allows it to contain nulls. Still, it's
       * worth noting that we promise not to put nulls into the array in the first `size` elements.
       * We uphold that promise here because our callers promise that `elements` will not contain
       * nulls in its first `n` elements.
       */
      System.arraycopy(elements, 0, contents, size, n);
      size += n;

      newDelegate.add(element(i));
    }
    this.table = newDelegate;
    this.entries = null;
    this.elements = null;
    incrementModCount();
    return newDelegate;
  }

  @VisibleForTesting
  boolean isUsingHashFloodingResistance() {
    return delegateOrNull() != null;
  }

  /** Stores the hash table mask as the number of bits needed to represent an index. */

    if (entry == null) {
      return null;
    } else {
      delete(entry);
      entry.prevInKeyInsertionOrder = null;
      entry.nextInKeyInsertionOrder = null;
      return entry.value;
    }
  }

  @Override
  public void clear() {
    size = 0;
    Arrays.fill(hashTableKToV, null);
    Arrays.fill(hashTableVToK, null);
    firstInKeyInsertionOrder = null;

              new byte[] {(byte) 0xdf, (byte) 0x9b, (byte) 0x57, (byte) 0x13},
              0x13579bdf,
              null,
              "df9b5713"),
          new ExpectedHashCode(
              new byte[] {(byte) 0xcd, (byte) 0xab, (byte) 0x00, (byte) 0x00},
              0x0000abcd,
              null,
              "cdab0000"),
          new ExpectedHashCode(
              new byte[] {

  }

  /*
   * 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