logger.warn("Failed to generate popular words.", e);
                }

                return wordList;
            });
        } catch (final ExecutionException e) {
            logger.warn("Failed to load popular words.", e);
        }
        return Collections.emptyList();
    }

    /**
     * Clears all cached popular word lists.
     */
    public void clearCache() {

import org.junit.jupiter.api.Tag;
import org.junit.jupiter.api.Test;

import io.restassured.RestAssured;
import io.restassured.path.json.JsonPath;

/**
 * Integration tests for the Popular Words API (/api/v1/popular-words)
 */
@Tag("it")
public class PopularWordsApiTests extends ITBase {

    @BeforeAll
    protected static void initAll() {
        RestAssured.baseURI = getFessUrl();
        settingTestToken();

        return tookMs;
    }

    /**
     * Returns the list of popular words.
     *
     * @return the list of popular words
     */
    public List<String> getWords() {
        return words;
    }

    /**
     * Returns the number of popular words.
     *
     * @return the number of popular words
     */
    public int getNum() {
        return num;
    }

    /**

  @JvmStatic // Despite being 'internal', this method is called by popular 3rd party SDKs.
  fun invalidatesCache(method: String): Boolean =
    (
      method == "POST" ||
        method == "PATCH" ||
        method == "PUT" ||
        method == "DELETE" ||
        method == "MOVE"
    )

  @JvmStatic // Despite being 'internal', this method is called by popular 3rd party SDKs.
  fun requiresRequestBody(method: String): Boolean =

import org.opensearch.search.rescore.QueryRescorerBuilder;
import org.opensearch.transport.client.Client;

/**
 * Represents a request for popular words. This class extends {@link Request} and is parameterized
 * with {@link PopularWordsResponse}. It allows specifying various criteria for retrieving popular words,
 * such as index, size, tags, roles, fields, languages, and exclusion words.
 *
 * <p>Key functionalities include:</p>
 * <ul>

## Key Features

- **Smart Query Suggestions**: Real-time auto-completion and search suggestions
- **Multi-language Support**: Built-in support for Japanese text processing with Kuromoji analyzer
- **Popular Words Analytics**: Track and analyze frequently searched terms

### OAuth 1 { #oauth-1 }

There was an OAuth 1, which is very different from OAuth2, and more complex, as it included direct specifications on how to encrypt the communication.

It is not very popular or used nowadays.

OAuth2 doesn't specify how to encrypt the communication, it expects you to have your application served with HTTPS.

/// tip

import org.junit.jupiter.api.Test

/**
 * Jetty HTTP client.
 *
 * https://www.eclipse.org/jetty/documentation/current/http-client.html
 *
 * Baseline test if we ned to validate OkHttp behaviour against other popular clients.
 */
class JettyHttpClientTest {
  private val client = HttpClient()

  @StartStop
  private val server = MockWebServer()

  @BeforeEach fun setUp() {
    client.start()
  }

- **[Installing Gradle](https://docs.gradle.org/current/userguide/installation.html)**
- **Build Projects for Popular Languages and Frameworks**:
  - [Java Applications](https://docs.gradle.org/current/samples/sample_building_java_applications.html)
  - [Java Modules](https://docs.gradle.org/current/samples/sample_java_modules_multi_project.html)

import org.junit.jupiter.api.extension.RegisterExtension

/**
 * Java HTTP Client.
 *
 * https://openjdk.java.net/groups/net/httpclient/intro.html
 *
 * Baseline test if we ned to validate OkHttp behaviour against other popular clients.
 */
class JavaHttpClientTest {
  @JvmField @RegisterExtension
  val platform = PlatformRule()

  @StartStop
  private val server = MockWebServer()

  @Test fun get() {
    // Not available