if (entry.getKey() == null) {
        tryDrainReferenceQueues();
        return null;
      }
      V value = entry.getValue();
      if (value == null) {
        tryDrainReferenceQueues();
        return null;
      }

      return value;
    }

    /**
     * Performs routine cleanup following a read. Normally cleanup happens during writes, or from

                null, null, null))
        .addEqualityGroup(
            Tables.<String, @Nullable Object, @Nullable Object>immutableCell("bar", null, null))
        .addEqualityGroup(
            Tables.<@Nullable Object, Integer, @Nullable Object>immutableCell(null, 2, null))
        .addEqualityGroup(
            Tables.<@Nullable Object, @Nullable Object, Character>immutableCell(null, null, 'b'))

    expected[getNullLocation()] = entry(null, v3());
    expectContents(expected);
  }

  @MapFeature.Require({SUPPORTS_PUT, ALLOWS_NULL_KEYS})
  public void testComputeIfPresent_nullKeySupportedAbsent() {
    assertNull(
        "computeIfPresent(null, function) should return null",
        getMap()
            .computeIfPresent(
                null,
                (k, v) -> {

        if (fessConfig.isValidUserCode(userCode)) {
            return userCode;
        }
        return null;
    }

    public void deleteUserCodeFromCookie(final HttpServletRequest request) {
        final String cookieValue = getUserCodeFromCookie(request);
        if (cookieValue != null) {
            updateCookie(StringUtil.EMPTY, 0);
        }
    }

   *
   * @param escaper the non-null escaper to test
   */
  public static void assertBasic(Escaper escaper) throws IOException {
    // Escapers operate on characters: no characters, no escaping.
    Assert.assertEquals("", escaper.escape(""));
    // Assert that escapers throw null pointer exceptions.
    try {
      escaper.escape((String) null);

   *
   * @param escaper the non-null escaper to test
   */
  public static void assertBasic(Escaper escaper) throws IOException {
    // Escapers operate on characters: no characters, no escaping.
    Assert.assertEquals("", escaper.escape(""));
    // Assert that escapers throw null pointer exceptions.
    try {
      escaper.escape((String) null);

   *     for the keys
   */
  @CanIgnoreReturnValue
  @CheckForNull
  public V erase(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
    Integer rowIndex = rowKeyToIndex.get(rowKey);
    Integer columnIndex = columnKeyToIndex.get(columnKey);
    if (rowIndex == null || columnIndex == null) {
      return null;
    }

   * either the full amount has been skipped or until the end of the stream is reached, whichever
   * happens first. Returns the total number of bytes skipped.
   */
  static long skipUpTo(InputStream in, long n) throws IOException {
    long totalSkipped = 0;
    // A buffer is allocated if skipSafely does not skip any bytes.
    byte[] buf = null;

    while (totalSkipped < n) {

        if (kid == null) {
            return;
        }

        if (children == null) {
            children = new MetadataTreeNode[nChildren];
        }

        children[index % nChildren] = kid;
    }

    // ------------------------------------------------------------------
    @Override
    public String toString() {
        return md == null ? "no metadata" : md.toString();
    }

         *
         * @param dependencies the direct dependencies, may be {@code null}
         * @return this request for chaining, never {@code null}
         */
        @Nonnull
        public DependencyResolverRequestBuilder dependencies(@Nullable List<DependencyCoordinates> dependencies) {
            this.dependencies = (dependencies != null) ? dependencies : Collections.emptyList();
            return this;
        }