public String html(String text) {
        if (text == null || text.isEmpty()) {
            return text;
        }
        return StringEscapeUtils.escapeHtml4(text);
    }
@Test
    public void testHtml() {
        EscapeTool instance = new EscapeTool();
        String text = null;
        String expResult = null;
        String result = instance.html(text);
        assertEquals(expResult, result);

        text = "";
        expResult = "";
        result = instance.html(text);
        assertEquals(expResult, result);

        text = "<div>";
        expResult = "&lt;div&gt;";
        result = instance.html(text);
        assertEquals(expResult, result);
    }