### Question:
Strings { public static boolean isEmpty(String s) { return s == null || s.length() == 0; }  static String zeros(int n); static String repeat(char value, int n); static boolean isEmpty(String s);  }### Answer:
@SuppressWarnings("ConstantConditions") @Test public void testEmptyString() { Assertions.assertTrue(isEmpty(null)); Assertions.assertTrue(isEmpty("")); Assertions.assertFalse(isEmpty("hello world")); }