### Question:
StringUtils { public static boolean isEmpty(String str) { return str == null || str.isEmpty(); }  static boolean isEmpty(String str); static List<String> split(String value, String separator); static Map<String, String> splitKeyValue(String... keyValue); static int findFirstIndexIn(String keyValue, String chars); static String addOffsets(String value, int spacesCount); static long dotCountIn(String line); static long symbolCountIn(String line, char symbol); static String unixLikePath(String path); static String toUnixPathSeparator(String line); static String escape(String value); static StringBuilder asStringBuilder(CharSequence line); static String getCauseMessage(Throwable t); static String getExceptionMessage(Throwable t); static boolean isBlank(String line);  }### Answer:
@Test void testIsEmpty() { assertTrue(isEmpty("")); assertTrue(isEmpty(null)); assertFalse(isEmpty(" ")); assertFalse(isEmpty("foo")); }