Strings { public static String trim(String s) { return s != null ? s.trim() : null; }  static String join(Iterable<?> col, String separator); static boolean isBlank(String s); static boolean isNotBlank(String s); static boolean isEmpty(String s); static boolean isNotEmpty(String s); static List<String> splitAndTrim(String value, String regex); static String trim(String s); static String trimToNull(String s); static String joinClassNames(Iterable<?> iterable); static Boolean toBoolean(String s);  }
@Test void testTrim() { assertNull(Strings.trim(null)); assertEquals("", Strings.trim("")); assertEquals("", Strings.trim(" ")); assertEquals("foo", Strings.trim(" foo ")); }