final FessMessages messages = new FessMessages();
        final FessMessages result = messages.addErrorsOperationAlreadyRunning("testProperty", "host1");
        assertNotNull(result);
        assertFalse(result.isEmpty());
        assertTrue(result.hasMessageOf("testProperty"));
    }

    @Test
    public void test_addErrorsOperationAlreadyRunning_withDifferentHosts() {
        final FessMessages messages1 = new FessMessages();

    private final transient VaMessenger<FessMessages> messageCode;

    /**
     * Creates a new InvalidQueryException with message code, message, and cause.
     *
     * @param messageCode the message code for localized error messages
     * @param message the detailed error message
     * @param cause the cause of the exception
     */

 * either express or implied. See the License for the specific language
 * governing permissions and limitations under the License.
 */
package org.codelibs.fess.exception;

import org.codelibs.fess.mylasta.action.FessMessages;
import org.lastaflute.web.validation.VaMessenger;

/**
 * Exception thrown during SSO (Single Sign-On) processing with message code support.
 *

src/main/resources/
├── fess_config.properties     # Main configuration
├── app.xml, fess.xml          # DI configuration
├── fess_*.xml                 # Feature-specific DI
├── fess_label_*.properties    # UI labels (i18n)
├── fess_message_*.properties  # Validation messages (i18n)
└── fess_indices/              # OpenSearch index mappings

src/main/webapp/WEB-INF/view/  # JSP templates
src/test/java/.../it/          # Integration tests (*Tests.java)
```

     * @return concatenated string of localized validation messages separated by spaces
     */
    protected String getMessage(final VaMessenger<FessMessages> validationMessagesLambda) {
        final FessMessages messages = new FessMessages();
        validationMessagesLambda.message(messages);
        return messageManager.toMessageList(request.getLocale() == null ? Locale.ENGLISH : request.getLocale(), messages)

     * 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":

     * 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":