@Test
public void testJoinReturningNonEmptyString() {

    List<String> arrayList = new ArrayList<String>();
    LinkedHashSet<String> linkedHashSet = new LinkedHashSet<String>(arrayList);
    linkedHashSet.add(")'<Mw@ZR0IYF_l%*>");
    linkedHashSet.add(null);
    String resultString = StringUtil.join(linkedHashSet, null);
    assertNotNull(resultString);
    assertEquals(")'<Mw@ZR0IYF_l%*>", resultString);
}