// 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) {

    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
);

    public boolean isUrlSet() {
        return URLSET.equals(type);
    }

    /**
     * Checks if this sitemap set is of type INDEX.
     * @return true if this is an INDEX, false otherwise
     */
    public boolean isIndex() {
        return INDEX.equals(type);
    }

    /**
     * Returns a string representation of this object.
     * @return A string representation.
     */
    @Override

  public @Nullable E lower(E element) {
    int index = headIndex(element, false) - 1;
    return (index == -1) ? null : elements.get(index);
  }

  @Override
  public @Nullable E floor(E element) {
    int index = headIndex(element, true) - 1;
    return (index == -1) ? null : elements.get(index);
  }

  @Override
  public @Nullable E ceiling(E element) {
    int index = tailIndex(element, true);

    }

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

    /**
     * Sets the OpenSearch index name.
     *
     * @param index The index name.
     */
    public void setIndex(final String index) {
        this.index = index;
    }

    /**

    }

    /**
     * Writes a 16-bit integer value to a byte array in little-endian format
     * @param val the value to write
     * @param dst the destination byte array
     * @param dstIndex the starting index in the destination array
     */
    public static void writeInt2(final long val, final byte[] dst, int dstIndex) {
        dst[dstIndex] = (byte) val;
        dstIndex++;
        dst[dstIndex] = (byte) (val >> 8);
    }

    level = DeprecationLevel.ERROR,
  )
  fun size(): Int = size

  /** Returns the field at `position`. */
  fun name(index: Int): String = commonName(index)

  /** Returns the value at `index`. */
  fun value(index: Int): String = commonValue(index)

  /** Returns an immutable case-insensitive set of header names. */
  fun names(): Set<String> {
    val result = TreeSet(String.CASE_INSENSITIVE_ORDER)

        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);
            }
          }