### Question:
SearchUtils { public static String trimToNull(String value) { if (value != null) { value = value.trim(); if (value.isEmpty()) value = null; } return value; }  static Properties loadProperties(String path); static String trimToNull(String value); static List<String> safeList(List<String> values); static boolean isBlank(String value); static boolean isBlank(Object value); static String convertJsonMapToString(Map<String, Object> jsonMapValue); static DateFormat getISODateFormat(); static Date dateFromISOString(String string, boolean silent); static boolean isDateAfter(Object date, int thresholdInMinutes); static Map<String, Object> convertToJsonMap(String jsonData); static Integer getIntegerFromJsonMap(Map<String, Object> map, String key); @SuppressWarnings("unchecked") static List<String> getListOfStringsFromJsonMap(Map<String, Object> map, String key); static void mergeJsonMaps(Map<String, Object> source, Map<String, Object> target); static Map<String, Object> collapseURLParams(MultivaluedMap<String, String> params); static boolean isMysqlDialect(String databaseProductName);  }### Answer:
@Test public void trimToNull() { Assert.assertNull(SearchUtils.trimToNull(null)); Assert.assertNull(SearchUtils.trimToNull("")); Assert.assertNull(SearchUtils.trimToNull(" ")); Assert.assertNull(SearchUtils.trimToNull(" \t ")); Assert.assertEquals("a", SearchUtils.trimToNull("a")); Assert.assertEquals("a", SearchUtils.trimToNull("a ")); Assert.assertEquals("a", SearchUtils.trimToNull(" a")); Assert.assertEquals("abcd aaa", SearchUtils.trimToNull(" abcd aaa \t ")); }