How to get the Chngeset assosiated workitem using java client library ?

hello team
I have a below code to get the comments from a ChangeSet .
IChangeSet cs = (IChangeSet) RTCtoMKS.rtcTeamRepo
.itemManager().fetchCompleteItem(
ch.changeSet(),
IItemManager.REFRESH, null);
Could you please tell me how do i get workitem details which is associated to a changeset ???