=== ":material-language-kotlin: Kotlin"
    ```kotlin

        }
        throw new SearchEngineClientException("client is not HttpClient.");
    }

    //
    // Fesen Client
    //

    /**
     * Gets the thread pool used by the client.
     *
     * @return the thread pool
     */
    @Override
    public ThreadPool threadPool() {
        return client.threadPool();
    }

    /**