* null} even for a map which supposedly does not contain null elements, if the key is not present
   * when {@code getValue()} is called.
   */
  final class EntryForKey extends AbstractMapEntry<K, V> {
    @ParametricNullness final K key;
    int index;

    EntryForKey(int index) {
      // The cast is safe because we call forEntry only for indexes that contain entries.
      this.key = uncheckedCastNullableTToT(keys[index]);

    try {
      getQueue().offer(null);
      fail("offer(null) should throw");
    } catch (NullPointerException expected) {
    }
    expectUnchanged();
    expectNullMissingWhenNullUnsupported("Should not contain null after unsupported offer(null)");
  }

   * Creates a <i>mutable</i> {@code CompactLinkedHashSet} instance containing the elements of the
   * given collection in the order returned by the collection's iterator.
   *
   * @param collection the elements that the set should contain
   * @return a new {@code CompactLinkedHashSet} containing those elements (minus duplicates)
   */
  public static <E extends @Nullable Object> CompactLinkedHashSet<E> create(
      Collection<? extends E> collection) {

        ImmutableSet.of(
            49, 51, 59, 163, 199, 321, 325, 363, 367, 469, 545, 561, 727, 769, 773, 781);
    for (int i = 1; i < 900; i += 2) {
      if (!falsePositives.contains(i)) {
        assertFalse("BF should not contain " + i, bf.mightContain(Integer.toString(i)));
      }
    }

    // Check that there are exactly 29824 false positives for this BF.
    int knownNumberOfFalsePositives = 29824;

  }

  @Override
  protected void expectMissing(Entry<K, V>... entries) {
    for (Entry<K, V> entry : entries) {
      assertFalse("Should not contain entry " + entry, actualContents().contains(entry));
      assertFalse(
          "Should not contain key " + entry.getKey() + " mapped to value " + entry.getValue(),
          equal(getMap().get(entry.getKey()), entry.getValue()));
    }
  }

      fail("putIfAbsent(null, value) should throw");
    } catch (NullPointerException expected) {
    }
    expectUnchanged();
    expectNullKeyMissingWhenNullKeysUnsupported(
        "Should not contain null key after unsupported putIfAbsent(null, value)");
  }

  @MapFeature.Require(value = SUPPORTS_PUT, absent = ALLOWS_NULL_VALUES)
  public void testPutIfAbsent_nullValueUnsupported() {
    try {

      fail("putIfAbsent(null, value) should throw");
    } catch (NullPointerException expected) {
    }
    expectUnchanged();
    expectNullKeyMissingWhenNullKeysUnsupported(
        "Should not contain null key after unsupported putIfAbsent(null, value)");
  }

  @MapFeature.Require(value = SUPPORTS_PUT, absent = ALLOWS_NULL_VALUES)
  public void testPutIfAbsent_nullValueUnsupportedAndKeyAbsent() {
    try {

    testDecodes(base64(), "Zg==", "f"); // proper padding length
    testDecodes(base64(), "Zg===", "f");
    testDecodes(base64(), "Zg====", "f");
  }

  public void testBase64InvalidDecodings() {
    // These contain bytes not in the decodabet.
    assertFailsToDecode(base64(), "A\u007f", "Unrecognized character: 0x7f");
    assertFailsToDecode(base64(), "Wf2!", "Unrecognized character: !");
    // This sentence just isn't base64() encoded.

          fail(
              rootLocaleFormat(
                  "Feature enum %s contains a class named "
                      + "'Require' but it is not an annotation.",
                  featureEnumClass));
        }
        return;
      }
    }
    fail(
        rootLocaleFormat(
            "Feature enum %s should contain an " + "annotation named 'Require'.",
            featureEnumClass));
  }

          return optional.orNull();
        }
      };

  /**
   * Sets.cartesianProduct doesn't allow sets that contain null, but we want null to mean "don't
   * call the associated CacheBuilder method" - that is, get the default CacheBuilder behavior. This
   * method wraps the elements in the input sets (which may contain null) as Optionals, calls
   * Sets.cartesianProduct with those, then transforms the result to unwrap the Optionals.
   */