```

### Exception Handling
```java
import org.codelibs.core.exception.*;

// Runtime exception wrappers eliminate try-catch boilerplate
try {
    // Code that might throw checked exceptions
    return ClassUtil.newInstance(className); // Wraps checked exceptions automatically
} catch (ClassNotFoundRuntimeException e) {
    // Handle the wrapped exception

            // Wait for completion
            for (Thread t : threads) {
                t.join();
            }

            // Verify thread safety - no unexpected exceptions
            assertEquals(0, exceptionCount.get(), "Should not have unexpected exceptions");

            // At least some threads should complete successfully
            assertTrue(successfulThreads.get() > 0, "At least some threads should complete successfully");

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

/**
 * System exception class for the Fess search engine.
 * This exception is thrown when system-level errors occur in the Fess application,
 * such as configuration errors, initialization failures, or critical runtime issues.
 */

    }

    /**
     * @throws Exception
     */
    public void testIsExist() throws Exception {
        assertEquals("1", true, ResourceUtil.isExist("CLMessages.properties"));
        assertEquals("2", false, ResourceUtil.isExist("hoge"));
    }

    /**
     * @throws Exception
     */
    public void testGetExtension() throws Exception {

import org.codelibs.core.beans.factory.BeanDescFactory;
import org.codelibs.core.exception.MethodNotFoundRuntimeException;
import org.junit.Test;

/**
 * @author higa
 * @author manhole
 */
public class BeanDescImplTest {

    /**
     * @throws Exception
     */
    @Test
    public void testPropertyDesc() throws Exception {
        final BeanDesc beanDesc = new BeanDescImpl(MyBean.class);

public class MessageFormatterTest {

    @Before
    public void setUp() throws Exception {
        LocaleUtil.setDefault(() -> Locale.JAPANESE);
    }

    @After
    public void tearDown() throws Exception {
        LocaleUtil.setDefault(null);
    }

    /**
     * @throws Exception
     */
    @Test
    public void testGetMessage() throws Exception {
        final String s = MessageFormatter.getMessage("EMSG0000");

 * </li>
 * <li>child exception summaries.</li>
 * </ul>
 */
public class ExceptionSummary {

    private Throwable exception;

    private String message;

    private String reference;

    private List<ExceptionSummary> children;

    public ExceptionSummary(Throwable exception, String message, String reference) {
        this(exception, message, reference, null);
    }

        // Then: Remove should throw UnsupportedOperationException
        UnsupportedOperationException exception = assertThrows(UnsupportedOperationException.class, iterator::remove);
        assertEquals("remove", exception.getMessage());
    }

    @Test
    @DisplayName("Close should be idempotent")
    void testClose_Idempotent() throws Exception {
        // Given: A valid iterator setup

  }

  public void testSetFailure() throws Exception {
    assertTrue(future.setException(new Exception("failure")));
    tester.testFailedFuture("failure");
  }

  public void testSetFailureNull() throws Exception {
    assertThrows(NullPointerException.class, () -> future.setException(null));
    assertFalse(future.isDone());
    assertTrue(future.setException(new Exception("failure")));
    tester.testFailedFuture("failure");
  }

    public void metadataInvalid(RepositoryEvent event) {
        Exception exception = event.getException();

        Object metadata;
        if (event.getMetadata().getFile() != null) {
            metadata = event.getMetadata().getFile();
        } else {
            metadata = event.getMetadata();
        }

        String errorType = " is invalid";
        if (exception instanceof FileNotFoundException) {