throws GraphConflictResolutionException {
        if (policy == null) {
            throw new GraphConflictResolutionException("no GraphConflictResolutionPolicy injected");
        }

        if (graph == null) {
            return null;
        }

        final MetadataGraphVertex entry = graph.getEntry();
        if (entry == null) {
            return null;
        }

        if (graph.isEmpty()) {

     * @return 削除されたエントリ。キーに対応するエントリがなかった場合は{@literal null}
     */
    protected Entry<K, V> removeMap(final Object key) {
        int hashCode = 0;
        int index = 0;

        if (key != null) {
            hashCode = key.hashCode();
            index = (hashCode & 0x7FFFFFFF) % mapTable.length;
            for (Entry<K, V> e = mapTable[index], prev = null; e != null; prev = e, e = e.next) {

        super(
            domain != null ? domain : tc.getConfig().getDefaultDomain(),
            username != null ? username : ( tc.getConfig().getDefaultUsername() != null ? tc.getConfig().getDefaultUsername() : "GUEST" ),
            password != null ? password : ( tc.getConfig().getDefaultPassword() != null ? tc.getConfig().getDefaultPassword() : "" ),
            (AuthenticationType) null);
        this.context = tc;
    }

    public ExtractData getText(final InputStream in, final Map<String, String> params) {
        if (in == null) {
            throw new CrawlerSystemException("The inputstream is null.");
        }

        final String password = getPassword(params);
        try (PDDocument document = PDDocument.load(in, password == null ? null : password)) {
            final StringWriter writer = new StringWriter();

     * @return A function that applies each function in the collection in order until a non-null result is found.
     *         If all functions return null, the composite function returns null.
     *
     * @throws NullPointerException if the input collection is null or contains null elements.
     */
    static Function<String, String> chain(Collection<? extends Function<String, String>> functions) {

            long id = 0;
            String line = null;
            while ((line = reader.readLine()) != null) {
                if (line.length() == 0 || line.charAt(0) == '#') {
                    if (updater != null) {
                        updater.write(line);
                    }
                    continue; // ignore empty lines and comments

            long id = 0;
            String line = null;
            while ((line = reader.readLine()) != null) {
                if (line.length() == 0 || line.charAt(0) == '#') {
                    if (updater != null) {
                        updater.write(line);
                    }
                    continue; // ignore empty lines and comments

      getMap().putIfAbsent(k0(), null);
    } catch (NullPointerException tolerated) {
    }
    expectUnchanged();
    expectNullValueMissingWhenNullValuesUnsupported(
        "Should not contain null after unsupported putIfAbsent(present, null)");
  }

  @MapFeature.Require({SUPPORTS_PUT, ALLOWS_NULL_VALUES})
  public void testPut_nullValueSupported() {
    Entry<K, V> nullValueEntry = entry(k3(), null);
    assertNull(

        synchronized (Deferred.this) {
            if (response != null || error != null) {
                return;
            }
            response = r;

            executeCallbacks = new ArrayList<>(doneCallbacks.size());
            Consumer<RESPONSE> callback;
            while ((callback = doneCallbacks.poll()) != null) {
                executeCallbacks.add(callback);
            }
        }

    assertNull("get(notPresent) should return null", get(k3()));
  }

  @MapFeature.Require(ALLOWS_NULL_KEY_QUERIES)
  public void testGet_nullNotContainedButAllowed() {
    assertNull("get(null) should return null", get(null));
  }

  @MapFeature.Require(absent = ALLOWS_NULL_KEY_QUERIES)
  public void testGet_nullNotContainedAndUnsupported() {
    try {
      assertNull("get(null) should return null or throw", get(null));