retrieve datacenter name in vsphere SDK 6.0

we were using 5.5 SDK and retrieving datacenter name .Now,with 6.0 SDK,the dc name code throws null pointer exception.Please suggest

serverConnection sc = si.getServerConnection();
         
         String dcName = null;
         _logger.info(" Server connection url :  " + sc.getUrl());
         Object dvsObject = MorUtil.createExactManagedEntity(sc, dvsMor);
        
        
        if(dvsObject != null && dvsObject instanceof DistributedVirtualSwitch){
            DistributedVirtualSwitch dvsObj = (DistributedVirtualSwitch)dvsObject;
            
            ManagedEntity me = dvsObj.getParent();
                
            ManagedObjectReference networkMor = me.getMOR();

The above line throws null pointer.Please suggest an example to retrieve the dc name from dvs object.

Is there any change in amanged object entity hierarchy and folder hierarchy in 6.0?

Marianne