public static String getContent(String content) {
        int index = content.indexOf(WORD_SEPARATOR);
        if (index == -1) {
            throw new IllegalArgumentException("content does not contain separator");
        }
        return content.substring(index + 1);
    }
@Test
    void testGetContentFail() {
        assertThrows(IllegalArgumentException.class, () -> {
            String content = "aabbb";
            ContentUtils.getContent(content);
        });
    }