@Test
public void testMultipleRoleKey() {

    assertNull(ZTSClient.multipleRoleKey(null));
    List<String> roles = new ArrayList<>();
    assertNull(ZTSClient.multipleRoleKey(roles));
    roles.add("role");
    assertEquals(ZTSClient.multipleRoleKey(roles), "role");
    roles.add("one");
    roles.add("apple");
    roles.add("yellow");
    roles.add("ones");
    assertEquals(ZTSClient.multipleRoleKey(roles), "apple,one,ones,role,yellow");
    List<String> unmRoles = Collections.unmodifiableList(roles);
    assertEquals(ZTSClient.multipleRoleKey(unmRoles), "apple,one,ones,role,yellow");
}