@GwtCompatible
public enum IteratorFeature {
  /** Support for {@link Iterator#remove()}. */
  SUPPORTS_REMOVE,
  /**
   * Support for {@link ListIterator#add(Object)}; ignored for plain {@link Iterator}
   * implementations.
   */
  SUPPORTS_ADD,
  /**
   * Support for {@link ListIterator#set(Object)}; ignored for plain {@link Iterator}
   * implementations.
   */
  SUPPORTS_SET;

  /**

     */
    public NumberConverter(final String pattern) {
        assertArgumentNotEmpty("pattern", pattern);
        this.pattern = pattern;
    }

    @Override
    public Object getAsObject(final String value) {
        if (StringUtil.isEmpty(value)) {
            return null;
        }
        try {
            return new DecimalFormat(pattern).parse(value);

        this.pattern = pattern;
    }

    @Override
    public Object getAsObject(final String value) {
        if (isEmpty(value)) {
            return null;
        }
        return TimestampConversionUtil.toSqlTimestamp(value, pattern);
    }

    @Override
    public String getAsString(final Object value) {
        if (value == null) {
            return null;
        }

    private static final Logger log = LoggerFactory.getLogger(DisniRdmaConnection.class);

    // DiSNI objects - would be actual DiSNI types in real implementation
    private final Object endpoint; // RdmaActiveEndpoint
    private final Object group; // RdmaActiveEndpointGroup<DisniRdmaEndpoint>

    /**
     * Create new DiSNI RDMA connection
     *
     * @param remote remote socket address

         * @return String
         */
        public String getBbb(final Object a) {
            return null;
        }

        /**
         * @return boolean
         */
        public boolean isCCC() {
            return true;
        }

        /**
         * @return Object
         */
        public Object isDdd() {
            return null;
        }

        /**

    SerializedForm(Multiset<? extends Object> multiset) {
      int distinct = multiset.entrySet().size();
      elements = new Object[distinct];
      counts = new int[distinct];
      int i = 0;
      for (Entry<? extends Object> entry : multiset.entrySet()) {
        elements[i] = entry.getElement();
        counts[i] = entry.getCount();
        i++;
      }
    }

    Object readResolve() {

            return delegate.entrySet();
          }

          @Override
          public boolean contains(@Nullable Object object) {
            if (object instanceof Entry<?, ?> && ((Entry<?, ?>) object).getKey() == null) {
              return false;
            }
            try {
              return super.contains(object);
            } catch (ClassCastException e) {
              return false;
            }
          }

        deleteLabel(crawlLabelId);

        final List<Map<String, Object>> jobLogList = readJobLog(NAME_PREFIX);
        for (Map<String, Object> elem : jobLogList) {
            deleteMethod("/api/admin/joblog/log/" + elem.get("id"));
        }

        final List<Map<String, Object>> crawlingInfoList = readCrawlingInfo(fileConfigId);
        for (Map<String, Object> elem : crawlingInfoList) {

  public static <T> Collector<T, ?, Optional<T>> toOptional() {
    return (Collector) TO_OPTIONAL;
  }

  private static final Object NULL_PLACEHOLDER = new Object();

  private static final Collector<@Nullable Object, ?, @Nullable Object> ONLY_ELEMENT =
      Collector.<@Nullable Object, ToOptionalState, @Nullable Object>of(
          ToOptionalState::new,
          (state, o) -> state.add((o == null) ? NULL_PLACEHOLDER : o),

    }
  }

  public void testPut_populated() {
    for (LoadingCache<Object, Object> cache : caches()) {
      // don't let the entries get GCed
      List<Entry<Object, Object>> warmed = warmUp(cache);
      for (int i = WARMUP_MIN; i < WARMUP_MAX; i++) {
        Entry<Object, Object> entry = warmed.get(i - WARMUP_MIN);
        Object newValue = new Object();
        assertSame(entry.getValue(), cache.asMap().put(entry.getKey(), newValue));