IDT SDK - getting object table(s) mapping

Hello,
 
How do I find out which tables (in data foundation) using object in business layer?
 
I try open universe business layer (blx) via sdk and get extra tables, but always return empty list.
 
My code:
 

 public void getMapping() {          SlContext context = null;          IEnterpriseSession enterpriseSession = null;          try {              context = SlContext.create();              enterpriseSession = CrystalEnterprise.getSessionMgr().logon(CMS_LOG_USER, CMS_LOG_PASS, CMS_LOG_HOST, CMS_AUTH_MODE);              context.getService(CmsSessionService.class).setSession(enterpriseSession);              LocalResourceService service = context.getService(LocalResourceService.class);              RelationalBusinessLayer businessLayer = (RelationalBusinessLayer) service.load(BLX_PATH);              RootFolder rootFolder = businessLayer.getRootFolder();              printObjectMapping(rootFolder);              service.close(businessLayer);          } catch (SDKException e) {              System.out.println("Error: " + e.getMessage());          }      }        protected static void printObjectMapping(BlItem biItem) {          if (biItem instanceof BusinessObject) {              BusinessObject elem = (BusinessObject) biItem;              RelationalBinding binding = (RelationalBinding) elem.getBinding();              System.out.println("Object " + elem.getName() + " using tables: " + binding.getExtraTables());          }          if (biItem instanceof BlContainer) {              for (BlItem item : ((BlContainer) biItem).getChildren()) {                  printObjectMapping(item);              }          }      }

 
BO 4.1 SP1

Any ideas?