### Question:
FunctionalUtils { public static <T> boolean isEmpty(Collection<T> collection) { return collection == null || collection.isEmpty(); } private  FunctionalUtils(); static boolean isEmpty(Collection<T> collection); static boolean isNotEmpty(Collection<T> collection); static boolean isEmpty(String string); static boolean isNotEmpty(String string); static Predicate<T> not(Predicate<T> predicate); static Consumer<T> toConsumer(UnsafeConsumer<T> unsafeConsumer, Logger logger); static BiConsumer<T, U> toBiConsumer(UnsafeBiConsumer<T, U> unsafeBiConsumer, Logger logger);  }### Answer:
@Test public void isEmptyTest() { assertEquals(true, FunctionalUtils.isEmpty((Collection<?>)null)); assertEquals(true, FunctionalUtils.isEmpty(Collections.emptyList())); assertEquals(true, FunctionalUtils.isEmpty((String)null)); assertEquals(true, FunctionalUtils.isEmpty("")); }