Want to Read all ChangeSet's associated with a Work Item

Say in my  Project Area's "SSFS On Premise" and "WMS" , i want to get all changeSets associated to a single Work Item say "344521".

Following is the code...kindly help

IWorkspaceManager iworkspaceManager = (IWorkspaceManager) repository.getClientLibrary(IWorkspaceManager.class);
            IWorkspaceSearchCriteria criteria1 = IWorkspaceSearchCriteria.FACTORY.newInstance();
            criteria1.setKind( IWorkspaceSearchCriteria.WORKSPACES );
            criteria1.setExactName( "SSFS On Premise" );
//                criteria1.setExactOwnerName("SSFS On Premise");
            List<IWorkspaceHandle> workspaceHandles = iworkspaceManager.findWorkspaces(criteria1, Integer.MAX_VALUE, monitor);    
            IWorkspaceHandle wh = workspaceHandles.get( 0 );
            IWorkspaceConnection workspaceConnection = iworkspaceManager.getWorkspaceConnection(wh, monitor);    
           
//           
            IChangeSetSearchCriteria changeSetSearchCriteria =     IChangeSetSearchCriteria.FACTORY.newInstance();
            IContextHandle workspaceContexthandle = workspaceConnection.getContextHandle();
           
            changeSetSearchCriteria.setContext(workspaceContexthandle);
           
            SimpleDateFormat format= new SimpleDateFormat("yyyyMMdd-hhmm");;
           
            changeSetSearchCriteria.setModifiedAfter(new Timestamp(format.parse("20130901").getTime()));
           
            List<IChangeSetHandle> changeSetHandles;
           
            try{
                changeSetHandles = SCMPlatform.getWorkspaceManager(repository).findChangeSets(changeSetSearchCriteria, 1024,monitor);
            }catch ( TeamRepositoryException  e){
                throw new RuntimeException(e);
            }

Also now how to read from changeSetHandlers ?