how to get Multilevel BOM in Windchill by using...

public Vector<object> getPartStructure(WTPart parentPart) throws Exception { 
        LatestConfigSpec lcs = new LatestConfigSpec();
        QueryResult usesLinks = StructHelper.service.navigateUses(parentPart, false);
        while(usesLinks.hasMoreElements()){
            WTPartUsageLink usageLink = (WTPartUsageLink) usesLinks.nextElement();
            WTPart childPart = (WTPart) lcs.process(VersionControlHelper.service.allVersionsOf(usageLink.getUses())).nextElement();
            getPartStructure(childPart);
        }
    }