Main operations: `suggest()`, `popularWords()`, `indexer()`, `createIndexIfNothing()`, `createNextIndex()`, `switchIndex()`, `removeDisableIndices()`

### SuggestIndexer (Indexing Engine)
Location: `src/main/java/org/codelibs/fess/suggest/index/SuggestIndexer.java`

Handles all indexing operations, content parsing, and word management (bad words, elevate words).

### SuggestSettings (Configuration)

import org.codelibs.fess.suggest.settings.SuggestSettings;
import org.opensearch.OpenSearchStatusException;
import org.opensearch.transport.client.Client;

/**
 * Internal operations class for content-based indexing functionality.
 * Handles indexing from query logs, documents, and search words.
 *
 * <p>This class is package-private and intended for internal use by SuggestIndexer.
 */
public class ContentIndexingOperations {

        // Add first document - should trigger indexing because cache size is 1
        Map<String, Object> dataMap1 = new HashMap<>();
        dataMap1.put("url", "http://example.com/test1");
        indexUpdateCallback.store(paramMap, dataMap1);
        assertEquals(1, indexingHelper.sendDocumentsCalled);

        // Add second document - should trigger indexing again
        Map<String, Object> dataMap2 = new HashMap<>();

/**
 * The SuggestIndexer class is responsible for indexing and managing suggest items in an OpenSearch index.
 * It provides methods to index, delete, and manage suggest items, including handling bad words and elevate words.
 *
 * <p>This class acts as a facade, delegating to internal operation classes for the actual work:
 * <ul>
 * <li>{@code IndexingOperations} - Core indexing functionality with bad word filtering</li>

 * governing permissions and limitations under the License.
 */
package org.codelibs.fess.suggest.index.operations;

/**
 * Encapsulates the context parameters commonly passed to content indexing operations.
 * Groups together index name, field configuration, and bad words to simplify method signatures.
 */
public class ContentIndexingContext {

    private final String index;

              // pseudo headers. Literal Header Field without Indexing - Indexed Name.
              writeInt(headerNameIndex, PREFIX_4_BITS, 0)
              writeByteString(value)
            }

            else -> {
              // Literal Header Field with Incremental Indexing - Indexed Name.
              writeInt(headerNameIndex, PREFIX_6_BITS, 0x40)
              writeByteString(value)

 * This class provides constants for system configuration, crawling and indexing defaults, user agent strings,
 * status values, field names, date/time formats, authentication types, and various reserved words and patterns.
 *
 * <p>Key constant categories include:</p>
 * <ul>
 * <li>System configuration property keys</li>
 * <li>Default values for crawling and indexing operations</li>
 * <li>User agent strings and patterns for web crawling</li>

errors.failed_to_change_password=Failed to change your password.
errors.unknown_version_for_upgrade=Unknown version for upgrade.
errors.failed_to_upgrade_from=Failed to upgrade from {0}.
errors.failed_to_reindex=Failed to start re-indexing from {0} to {1}.
errors.failed_to_rebuild_config_index=Failed to rebuild config indices.
errors.no_target_index_selected=Please select at least one target index to rebuild.

errors.failed_to_change_password=Failed to change your password.
errors.unknown_version_for_upgrade=Unknown version for upgrade.
errors.failed_to_upgrade_from=Failed to upgrade from {0}.
errors.failed_to_reindex=Failed to start re-indexing from {0} to {1}.
errors.failed_to_rebuild_config_index=Failed to rebuild config indices.
errors.no_target_index_selected=Please select at least one target index to rebuild.

labels.crawling_info_WebFsIndexExecTime=Indexing Execution Time (Web/File)
labels.crawling_info_WebFsIndexSize=Index Size (Web/File)
labels.crawling_info_DataCrawlExecTime=Crawl Execution Time (Data Store)
labels.crawling_info_DataCrawlStartTime=Crawl Start Time (Data Store)
labels.crawling_info_DataCrawlEndTime=Crawl End Time (Data Store)
labels.crawling_info_DataIndexExecTime=Indexing Execution Time (Data Store)