Add approver and subscriber to a workitem in Rational Team Concert Extension

Another function that i use in Extending Rational Team Concert :

 private void addApprover(ISaveParameter saveParameter, String superior1, String superior2, String approvalType, String approverListName)  
   throws TeamRepositoryException  
  {  
   IWorkItem newState = (IWorkItem)saveParameter.getNewState();  
   IContributorHandle owner = newState.getOwner();  
   if (owner != null)  
   {  
    IContributorHandle superiorHandle = getSuperiorHandle(superior1);  
    if (superiorHandle == null) {  
     System.out.println("----internal user not found----");  
    }  
    IApprovals approvals = newState.getApprovals();  
    IApprovalDescriptor descriptor = approvals.createDescriptor(approvalType, approverListName);  
    IApproval approval = approvals.createApproval(descriptor, superiorHandle);  
    approvals.add(approval);     
   }  
  }  
  private IContributorHandle getSuperiorHandle(String superiorID)  
   throws TeamRepositoryException  
  {  
   IContributorService contributorService = (IContributorService)getService(IContributorService.class);  
   return contributorService.fetchContributorByUserId(superiorID);  
  }  

and this one is to add the subscriber

  IContributorHandle ownerToSubscribe = blockingWorkItem.getOwner();  
  if (ownerToSubscribe != null) {  
      ISubscriptions subscriptions = thisWorkItem.getSubscriptions();  
      subscriptions.add(ownerToSubscribe);  
  }