code: public static UOWScopeCallback createUserTransactionCallback() {
          if (tc.isEntryEnabled())
              Tr.entry(tc, "createUserTransactionCallback");
  
          if (userTranCallback == null) {
              userTranCallback = new LTCUOWCallback(UOW_TYPE_TRANSACTION);
          }
  
          if (tc.isEntryEnabled())
              Tr.exit(tc, "createUserTransactionCallback", userTranCallback);
          return userTranCallback;
      }
docs: may be different in derived classes