.setLevel(Level.ERROR)
                .setMessage(new SimpleMessage("test message 1"))
                .build();

        LogEvent event2 = Log4jLogEvent.newBuilder()
                .setLoggerName("another.logger.sub")
                .setLevel(Level.ERROR)
                .setMessage(new SimpleMessage("test message 2"))
                .build();

        assertEquals(3, events.size());
        assertEquals("error 1", events.get(0).getMessage());
        assertEquals("error 2", events.get(1).getMessage());
        assertEquals("error 3", events.get(2).getMessage());
    }

    @Test
    public void test_append_warnAppender_errorEvent() {

        assertNotSame(exception2, exception3);
        assertNotSame(exception1, exception3);

        assertEquals("First instance", exception1.getMessage());
        assertEquals("Second instance", exception2.getMessage());
        assertEquals("Third instance", exception3.getMessage());
    }

    @Test
    public void test_specialCharactersInMessage() {
        // Test with special characters in message

        assertNotSame(exception1, exception2);
        assertFalse(exception1.getMessage().equals(exception2.getMessage()));
        assertEquals("User is not found: user1", exception1.getMessage());
        assertEquals("User is not found: user2", exception2.getMessage());
    }

        assertEquals("Type1", exception1.getType());
        assertEquals("Message1", exception1.getMessage());
        assertEquals("Type2", exception2.getType());
        assertEquals("Message2", exception2.getMessage());

        assertNotSame(exception1, exception2);
    }

    @Test
    public void test_serialVersionUID() {

        assertTrue(exception instanceof FessSystemException);
    }

    @Test
    public void test_constructorWithNullMessage() {
        // Test constructor with null message
        SearchQueryException exception = new SearchQueryException((String) null);

        assertNull(exception.getMessage());
        assertNull(exception.getCause());

        assertEquals(messageCode, exception3Params.getMessageCode());
        assertEquals(message, exception3Params.getMessage());
        assertEquals(cause, exception3Params.getCause());

        assertEquals(messageCode, exception2Params.getMessageCode());
        assertEquals(message, exception2Params.getMessage());
        assertNull(exception2Params.getCause());
    }

        // Execute
        final SsoMessageException exception = new SsoMessageException(messageCode, message, cause);

        // Verify
        assertNotNull(exception);
        assertEquals(message, exception.getMessage());
        assertEquals(cause, exception.getCause());
        assertEquals(messageCode, exception.getMessageCode());
    }

    @Test
    public void test_constructor_withMessageCodeAndMessage() {
        // Setup

        assertEquals("Error message", exception.getMessage());
        assertNull(exception.getCause());
    }

    @Test
    public void test_constructorWithMessageAndCause() {
        final RuntimeException cause = new RuntimeException("Root cause");
        final LlmException exception = new LlmException("Error occurred", cause);
        assertEquals("Error occurred", exception.getMessage());
        assertSame(cause, exception.getCause());

        assertEquals(servletException, runtimeException.getCause());

        // Verify that the message is preserved from the cause
        assertTrue(runtimeException.getMessage().contains(ServletException.class.getName()));
        assertTrue(runtimeException.getMessage().contains(errorMessage));
    }

    @Test
    public void test_constructor_withServletExceptionWithCause() {
        // Create a root cause exception