return actionClass;
    }

    /**
     * Overrides fillInStackTrace to return null for performance optimization.
     * This prevents stack trace generation for this exception type.
     *
     * @return null to skip stack trace generation
     */
    @Override
    public synchronized Throwable fillInStackTrace() {
        return null;
    }

    @Test
    public void test_fillInStackTrace() {
        // Test fillInStackTrace method
        UnsupportedSearchException exception = new UnsupportedSearchException("Stack trace test");

        StackTraceElement[] originalStackTrace = exception.getStackTrace();
        assertNotNull(originalStackTrace);

        Throwable filled = exception.fillInStackTrace();
        assertSame(exception, filled);

        assertTrue(foundTestMethod);
    }

    @Test
    public void test_fillInStackTrace() {
        // Test that fillInStackTrace works properly
        JobNotFoundException exception = new JobNotFoundException("Fill stack trace test");

        Throwable filled = exception.fillInStackTrace();

        assertNotNull(filled);
        assertEquals(exception, filled);
        assertNotNull(filled.getStackTrace());

        assertNull(localizedMessage);
    }

    @Test
    public void test_fillInStackTrace() {
        // Test fillInStackTrace method
        DictionaryExpiredException exception = new DictionaryExpiredException();
        Throwable result = exception.fillInStackTrace();

        assertNotNull(result);
        assertSame(exception, result);

        StackTraceElement[] stackTrace = result.getStackTrace();

        assertTrue(toString.contains(message));
    }

    @Test
    public void test_fillInStackTrace() {
        // Test fillInStackTrace method
        DataStoreException exception = new DataStoreException("Stack trace test");
        Throwable filled = exception.fillInStackTrace();

        assertNotNull(filled);
        assertEquals(exception, filled);
        assertNotNull(filled.getStackTrace());

  private static final class TimeoutFutureException extends TimeoutException {
    private TimeoutFutureException(String message) {
      super(message);
    }

    @Override
    public synchronized Throwable fillInStackTrace() {
      setStackTrace(new StackTraceElement[0]);
      return this; // no stack trace, wouldn't be useful anyway
    }
  }

  @Override
  protected @Nullable String pendingToString() {