public static boolean equals(String a, String b) {
        if (a == null) {
            return b == null;
        }
        return a.equals(b);
    }
@Test
    public void testEquals() {
        Assert.assertFalse(StringUtils.equals(null, ""));
        Assert.assertFalse(StringUtils.equals("foo", "bar"));
        Assert.assertFalse(StringUtils.equals("foo", "FOO"));

        Assert.assertTrue(StringUtils.equals(null, null));
        Assert.assertTrue(StringUtils.equals("foo", "foo"));
    }