public static String truncateContent(String content) {
        if (content == null) {
            return "";
        } else if (content.length() <= LIMIT_CONTENT_SIZE) {
            return content;
        } else {
            return content.substring(0, 100) + "...";
        }
    }
@Test
    void testTruncateContent() {
        String content = "test";
        String result = ContentUtils.truncateContent(content);
        assertEquals(content, result);
        
        String content2 = "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz";
        String result2 = ContentUtils.truncateContent(content2);
        String expected = "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuv...";
        assertEquals(expected, result2);
        
        assertEquals("", ContentUtils.truncateContent(null));
    }