@Test
    public void test_htmlContent_defaultValue() {
        final ChatMessage message = new ChatMessage();
        assertNull(message.getHtmlContent());
    }

    @Test
    public void test_htmlContent_setAndGet() {
        final ChatMessage message = new ChatMessage();
        final String htmlContent = "<p>This is <strong>HTML</strong> content</p>";

        message.setHtmlContent(htmlContent);