How to find work item change sets details plain java api?

Question

I am using the below code and it returns number of track change links and I am sure it contains change set also But I am not able to find the correct api to get that data. Please help

IReference reference = linkManager.referenceFactory().createReferenceToItem(workItem.getItemHandle());
ILinkQueryPage childPage;

childPage = linkManager.findLinks(reference, monitor);
ILinkCollection linkCollection = childPage.getAllLinksFromHereOn();
Collection<ILink> links1 = linkCollection.getLinksById("com.ibm.team.workitem.linktype.scm.tracksChanges");

for (Object wI : links1) {
    ILink link = (ILink) wI;
    Object source = link.getSourceRef().resolve();
    IItemHandle itemHandle = (IItemHandle) link.getSourceRef().resolve();

    if (source instanceof IChangeSetHandle) {
        changeSet = (IChangeSet) repo.itemManager().fetchCompleteItem(itemHandle,
            IItemManager.DEFAULT, monitor);
        System.out.println("changeset---1"+changeSet);
    }
}