### Question:
FuncUtils { public static String mkString(Iterable<String> list, String split) { if (null == list || StringUtils.isEmpty(split)){ return null; } StringBuilder sb = new StringBuilder(); boolean first = true; for (String item : list) { if (first) { first = false; } else { sb.append(split); } sb.append(item); } return sb.toString(); }  static String mkString(Iterable<String> list, String split);  }### Answer:
@Test public void testMKString() { Iterable<String> users = Arrays.asList("user1", "user2", "user3"); String split = "|"; String result = FuncUtils.mkString(users, split); logger.info(result); assertEquals("user1|user2|user3", result); result = FuncUtils.mkString(null, split); assertNull(result); result = FuncUtils.mkString(users, null); assertNull(result); }