/**
 * Abstract base class for thumbnail generators.
 * Provides common functionality for thumbnail generation implementations.
 */
public abstract class BaseThumbnailGenerator implements ThumbnailGenerator {
    private static final Logger logger = LogManager.getLogger(BaseThumbnailGenerator.class);

    /** Map of conditions for thumbnail generation. */
    protected final Map<String, String> conditionMap = new HashMap<>();

     */
    protected static class Options {
        /**
         * Session ID for filtering thumbnail generation.
         */
        @Option(name = "-s", aliases = "--sessionId", metaVar = "sessionId", usage = "Session ID")
        protected String sessionId;

        /**
         * Name identifier for the thumbnail generation task.
         */
        @Option(name = "-n", aliases = "--name", metaVar = "name", usage = "Name")

    protected final List<ThumbnailGenerator> generatorList = new ArrayList<>();

    /**
     * Queue for thumbnail generation tasks containing URL, content, and path tuples.
     */
    protected BlockingQueue<Tuple3<String, String, String>> thumbnailTaskQueue;

    /**
     * Flag indicating whether thumbnail generation is currently in progress.
     */
    protected volatile boolean generating;

    private Thread thumbnailQueueThread;

     * This implementation is empty as no cleanup is required.
     */
    @Override
    public void destroy() {
    }

    /**
     * Creates a thumbnail generation task for the specified document.
     *
     * @param path the file path or URL of the document
     * @param docMap the document metadata map containing field values

 */
public class CommandGenerator extends BaseThumbnailGenerator {
    private static final Logger logger = LogManager.getLogger(CommandGenerator.class);

    /** List of command strings to execute for thumbnail generation. */
    protected List<String> commandList;

    /** Timeout for command execution in milliseconds. */
    protected long commandTimeout = 30 * 1000L;// 30sec

 */
public class GenerateThumbnailJob extends ExecJob {
    /** Logger for this class. */
    static final Logger logger = LogManager.getLogger(GenerateThumbnailJob.class);

    /** Number of threads to use for thumbnail generation. */
    protected int numOfThreads = 1;

    /** Flag indicating whether to perform cleanup operations. */
    protected boolean cleanup = false;

    /**
     * Default constructor for the GenerateThumbnailJob.

├── fess_message_*.properties  # Validation messages (i18n)
└── fess_indices/              # OpenSearch index mappings

src/main/webapp/WEB-INF/view/  # JSP templates
```

## DBFlute Code Generation

DBFlute generates type-safe data access code for OpenSearch indices:

```bash
mvn dbflute:freegen
```

Generated code:
- `opensearch/{index}/bsentity/` - Base entities (do not edit)

/**
 * View class for managing facet query configurations and their display.
 * This class handles the setup and organization of query facets for the search interface,
 * including automatic generation of file type facets and custom query mappings.
 */
public class FacetQueryView {
    /** Logger instance for this class */
    private static final Logger logger = LogManager.getLogger(FacetQueryView.class);

# out.
FESS_JAVA_OPTS="$FESS_JAVA_OPTS -Xms${FESS_MIN_MEM}"
FESS_JAVA_OPTS="$FESS_JAVA_OPTS -Xmx${FESS_MAX_MEM}"
FESS_JAVA_OPTS="$FESS_JAVA_OPTS -XX:MaxMetaspaceSize=256m -XX:CompressedClassSpaceSize=32m"

# new generation
if [ "x$FESS_HEAP_NEWSIZE" != "x" ]; then
    FESS_JAVA_OPTS="$FESS_JAVA_OPTS -Xmn${FESS_HEAP_NEWSIZE}"
fi

# set to headless, just in case
FESS_JAVA_OPTS="$FESS_JAVA_OPTS -Djava.awt.headless=true"

REM out.
set FESS_JAVA_OPTS=%FESS_JAVA_OPTS% -Xms%FESS_MIN_MEM% -Xmx%FESS_MAX_MEM%
set FESS_JAVA_OPTS=%FESS_JAVA_OPTS% -XX:MaxMetaspaceSize=256m -XX:CompressedClassSpaceSize=32m

REM new generation
if NOT "%FESS_HEAP_NEWSIZE%" == "" (
set FESS_JAVA_OPTS=%FESS_JAVA_OPTS% -Xmn%FESS_HEAP_NEWSIZE%
)

REM max direct memory
if NOT "%FESS_DIRECT_SIZE%" == "" (