// Call the next interceptor in the chain.
    val next = copy(index = index + 1, request = request)
    val interceptor = interceptors[index]

    @Suppress("USELESS_ELVIS")
    val response =
      interceptor.intercept(next) ?: throw NullPointerException(
        "interceptor $interceptor returned null",
      )

    if (exchange != null) {
      check(index + 1 >= interceptors.size || next.calls == 1) {

        this.index = index;
        this.tookMs = tookMs;
        this.words = words;
        num = words.size();
        this.total = total;
        this.items = items;
    }

    /**
     * Returns the index name.
     * @return The index name.
     */
    public String getIndex() {
        return index;
    }

    /**
     * Returns the time taken in milliseconds.
     * @return The time taken.

    public @Nullable V get(@Nullable Object key) {
      Integer index = keyIndex.get(key);
      if (index == null) {
        return null;
      } else {
        return getValue(index);
      }
    }

    @Override
    public @Nullable V put(K key, @ParametricNullness V value) {
      Integer index = keyIndex.get(key);
      if (index == null) {
        throw new IllegalArgumentException(

    });
```

## Advanced Usage

### Index from Existing Documents

```java
import org.codelibs.fess.suggest.index.contents.document.ESSourceReader;

// Index suggestions from existing Elasticsearch documents
DocumentReader reader = new ESSourceReader(
    client,
    suggester.settings(),
    "content-index",        // source index
    "document"             // document type
);

├── api/                       # REST API endpoints
├── opensearch/                # OpenSearch integration
│   ├── config/                # Config index (crawl configs, schedules)
│   ├── log/                   # Log index
│   ├── user/                  # User index
│   ├── exbhv/                 # Extended behaviors (repositories)
│   └── exentity/              # Extended entities (domain models)

    runRemoveTest(getNumElements() - 1);
  }

  private void runRemoveTest(int index) {
    assertEquals(
        Platform.format("remove(%d) should return the element at index %d", index, index),
        getList().get(index),
        getList().remove(index));
    List<E> expected = copyToList(createSamplesArray());
    expected.remove(index);
    expectContents(expected);
  }

     * Returns the entry at the specified position.
     *
     * @param index the index
     * @return the entry
     */
    public Entry getEntry(final int index) {
        assertIndex(0 <= index && index < size, "Index: " + index + ", Size: " + size);
        Entry e = header;
        if (index < size / 2) {
            for (int i = 0; i <= index; i++) {
                e = e.next;
            }
        } else {

        PopularWordsResponse response = new PopularWordsResponse("my-index", 50, words, 5, new ArrayList<>());

        assertEquals("my-index", response.getIndex());
    }

    @Test
    public void test_getTookMs() throws Exception {
        List<String> words = new ArrayList<>();
        PopularWordsResponse response = new PopularWordsResponse("test-index", 123, words, 5, new ArrayList<>());

        private int index = -1;
        private final int maxIndex = keyToIndex().size();

        @Override
        protected @Nullable Entry<K, V> computeNext() {
          for (index++; index < maxIndex; index++) {
            V value = getValue(index);
            if (value != null) {
              return immutableEntry(getKey(index), value);
            }
          }

   * Atomically adds the given value to the element at index {@code i}.
   *
   * @param i the index
   * @param delta the value to add
   * @return the previous value
   */
  @CanIgnoreReturnValue
  public final double getAndAdd(int i, double delta) {
    return getAndAccumulate(i, delta, Double::sum);
  }

  /**
   * Atomically adds the given value to the element at index {@code i}.
   *
   * @param i the index