How use work item API to add approvals?

	private void createApproval(IWorkItem newState,

			IAdvisorInfoCollector collector) throws TeamRepositoryException {

		IContributorHandle owner = newState.getOwner();

		IContributorHandle approver = null;

		approver = getApproverExternalByOwner(owner);

		// getApproverFromTeamHierarchy(owner,newState);



		if (null == approver) {

			IAdvisorInfo info = collector.createProblemInfo(

					"Unable to create the Approval",

					"Unable to find an approver for the work item", ID);

			collector.addInfo(info);

			return;

		}

		IApprovals approvals = newState.getApprovals();

		IApprovalDescriptor descriptor = approvals.createDescriptor(

				WorkItemApprovals.REVIEW_TYPE.getIdentifier(), APPROVAL_NAME);

		IApproval approval = approvals.createApproval(descriptor, approver);

		approvals.add(approval);

	}