public EngineInfo getEngineInfo() {
        if (client instanceof final HttpClient httpClient) {
            return httpClient.getEngineInfo();
        }
        throw new SearchEngineClientException("client is not HttpClient.");
    }

    //
    // Fesen Client
    //

    @Override
    public ThreadPool threadPool() {
        return client.threadPool();
    }

    @Override

import org.codelibs.fess.entity.SearchRenderData;
import org.codelibs.fess.entity.SearchRequestParams;
import org.codelibs.fess.entity.SearchRequestParams.SearchRequestType;
import org.codelibs.fess.es.client.SearchEngineClient;
import org.codelibs.fess.exception.InvalidAccessTokenException;
import org.codelibs.fess.exception.InvalidQueryException;
import org.codelibs.fess.exception.ResultOffsetExceededException;