@Test public void emptiness() throws Exception { assertThat(isNullOrEmpty((String) null)).isTrue(); assertThat(isNullOrEmpty("")).isTrue(); assertThat(isNullOrEmpty(" ")).isTrue(); assertThat(isNullOrEmpty(" a ")).isFalse(); assertThat(isNullOrEmpty("a")).isFalse(); assertThat(isNullOrEmpty((Map) null)).isTrue(); Map<String, Object> map = new LinkedHashMap<>(20); assertThat(isNullOrEmpty(map)).isTrue(); map.put("foo", "bar"); assertThat(isNullOrEmpty(map)).isFalse(); map.clear(); assertThat(isNullOrEmpty(map)).isTrue(); assertThat(isNullOrEmpty((Collection) null)).isTrue(); Collection<String> collection = new ArrayList<>(); assertThat(isNullOrEmpty(collection)).isTrue(); collection.add("foo"); assertThat(isNullOrEmpty(collection)).isFalse(); collection.clear(); assertThat(isNullOrEmpty(collection)).isTrue(); }