public static boolean isEmpty(final CharSequence cs) {
        return cs == null || cs.length() == 0;
    }
@Test
    public void testIsEmpty() {
        assertThat(StringUtils.isEmpty(null)).isTrue();
        assertThat(StringUtils.isEmpty("abc")).isFalse();
        assertThat(StringUtils.isEmpty("")).isTrue();
        assertThat(StringUtils.isEmpty(" ")).isFalse();
    }