### Question:
ObjectUtil { public static void requireNotEmpty(String param, String message) { if (StringUtils.isEmpty(param)) { throw new IllegalArgumentException(message); } }  static void requireNotNull(Object param, String message); static void requireNotEmpty(String param, String message); Map<String, String> getThreadContextMap(ThreadLocal<Map<String, String>> threadConfigurationContext); Map<String, Object> mergeConfigurations(Map<String, Object> firstMap, Map<String, Object> secondMap); static String getMethodIdentifier(Method method);  }### Answer:
@Test public void testRequireNotEmpty() { try { ObjectUtil.requireNotEmpty(null, "Parameter can't be empty"); fail(); } catch (IllegalArgumentException e) { assertEquals("Parameter can't be empty", e.getMessage()); } try { ObjectUtil.requireNotEmpty(new String(), "Parameter can't be empty"); fail(); } catch (IllegalArgumentException e) { assertEquals("Parameter can't be empty", e.getMessage()); } ObjectUtil.requireNotEmpty(" ", "Parameter can't be empty"); }