final SystemHelper systemHelper = ComponentUtil.getSystemHelper();
        final long startTime = systemHelper.getCurrentTimeAsLong();

        final IndexUpdateCallback indexUpdateCallback = ComponentUtil.getComponent(IndexUpdateCallback.class);

        final List<String> sessionIdList = new ArrayList<>();
        dataCrawlingThreadList.clear();

    protected IndexUpdateCallback indexUpdateCallback;

    /** Factory for creating crawler clients to handle different URL schemes. */
    protected CrawlerClientFactory crawlerClientFactory;

    /**
     * List of URLs to be deleted, cached for batch processing.
     * All access is synchronized via indexUpdateCallback lock.
     */

import org.codelibs.core.lang.StringUtil;
import org.codelibs.core.lang.ThreadUtil;
import org.codelibs.core.misc.Pair;
import org.codelibs.fess.Constants;
import org.codelibs.fess.ds.callback.IndexUpdateCallback;
import org.codelibs.fess.entity.DataStoreParams;
import org.codelibs.fess.helper.CrawlingInfoHelper;
import org.codelibs.fess.helper.SystemHelper;
import org.codelibs.fess.mylasta.direction.FessConfig;

import jakarta.annotation.PostConstruct;

/**
 * Implementation of IndexUpdateCallback for handling document indexing operations.
 * This class manages the process of updating the search index with documents from
 * data stores, including bulk operations, document transformation, and error handling.
 */
public class IndexUpdateCallbackImpl implements IndexUpdateCallback {