public static String substringAfter(String str, String separator) {
        if ((str == null) || (str.length() == 0)) {
            return str;
        }
        if (separator == null) {
            return EMPTY;
        }
        int pos = str.indexOf(separator);
        if (pos < 0) {
            return EMPTY;
        }
        return str.substring(pos + separator.length());
    }
@Test
    public void testSubstringAfter() {
        Assert.assertEquals(null, StringUtils.substringAfter(null, "*"));
        Assert.assertEquals("", StringUtils.substringAfter("", "*"));
        Assert.assertEquals("", StringUtils.substringAfter("*", null));
        Assert.assertEquals("bc", StringUtils.substringAfter("abc", "a"));
        Assert.assertEquals("cba", StringUtils.substringAfter("abcba", "b"));
        Assert.assertEquals("", StringUtils.substringAfter("abc", "c"));
        Assert.assertEquals("", StringUtils.substringAfter("abc", "d"));
        Assert.assertEquals("abc", StringUtils.substringAfter("abc", ""));
    }