// Setup - test with different message codes
        final String message = "Query validation error";
        final VaMessenger<FessMessages> unknownErrorCode =
                messages -> messages.addErrorsInvalidQueryUnknown(UserMessages.GLOBAL_PROPERTY_KEY);
        final VaMessenger<FessMessages> parseErrorCode =
                messages -> messages.addErrorsInvalidQueryParseError(UserMessages.GLOBAL_PROPERTY_KEY);

        // Execute

        // Setup - test with different message codes
        final String message = "Test message";
        final VaMessenger<FessMessages> loginErrorCode = messages -> messages.addErrorsSsoLoginError(UserMessages.GLOBAL_PROPERTY_KEY);
        final VaMessenger<FessMessages> logoutErrorCode = messages -> messages.addSuccessSsoLogout(UserMessages.GLOBAL_PROPERTY_KEY);

        // Execute

        assertEquals("{errors.front_footer}", FessMessages.ERRORS_front_footer);
        assertEquals("{errors.front_prefix}", FessMessages.ERRORS_front_prefix);
        assertEquals("{errors.front_suffix}", FessMessages.ERRORS_front_suffix);
        assertEquals("{errors.header}", FessMessages.ERRORS_HEADER);
        assertEquals("{errors.footer}", FessMessages.ERRORS_FOOTER);

        final List<VaMessenger<FessMessages>> errorMessages = new ArrayList<>();
        AdminSearchlistAction.validateFields(doc, errorMessages::add);

        assertFalse(errorMessages.isEmpty());

        // Verify error messages use field names without doc. prefix
        final FessMessages messages = new FessMessages();
        errorMessages.forEach(m -> m.message(messages));

    @Override
    public ActionValidator<FessMessages> createValidator() {
        return systemHelper.createValidator(requestManager, this::createMessages, myValidationGroups());
    }

    /**
     * Creates a new messages instance for handling validation and user messages.
     * This method can be called by the application to create message containers.
     *
     * @return a new FessMessages instance
     */
    @Override

         * @return This ApiErrorResponse instance.
         */
        public ApiErrorResponse message(final VaMessenger<FessMessages> validationMessagesLambda) {
            final FessMessages messages = new FessMessages();
            validationMessagesLambda.message(messages);
            message = ComponentUtil.getMessageManager()

     * Adds a password validation error message to the messages object based on the error key.
     *
     * @param messages the FessMessages object to add the error to
     * @param errorKey the error key identifying the type of password validation error
     */
    protected void addPasswordValidationError(final FessMessages messages, final String errorKey) {
        switch (errorKey) {
        case "errors.password_length":

import org.codelibs.fess.app.service.GroupService;
import org.codelibs.fess.app.web.CrudMode;
import org.codelibs.fess.app.web.base.FessAdminAction;
import org.codelibs.fess.mylasta.action.FessMessages;
import org.codelibs.fess.opensearch.user.exentity.Group;
import org.codelibs.fess.util.ComponentUtil;
import org.codelibs.fess.util.RenderDataUtil;
import org.dbflute.optional.OptionalEntity;

manage.bat     # On Windows
# Select option 23 (generate)
```

This will regenerate:
- `src/main/java/org/codelibs/fess/mylasta/action/FessLabels.java`
- `src/main/java/org/codelibs/fess/mylasta/action/FessMessages.java`
- `src/main/java/org/codelibs/fess/mylasta/direction/FessProp.java`

### 5. Rebuild the Project

```bash
mvn clean package
```

### 6. Test the New Language

1. **Start Fess:**

     * @param runtimeGroups   The runtime groups.
     * @return A new action validator.
     */
    public ActionValidator<FessMessages> createValidator(final RequestManager requestManager,
            final UserMessagesCreator<FessMessages> messagesCreator, final Class<?>[] runtimeGroups) {
        return new FessActionValidator<>(requestManager, messagesCreator, runtimeGroups);
    }

    /**