code: public TransactionManager getTransactionManager() {
          TransactionManager transMgr = null;
          try {
              String jndiName = ApplicationContext.getNamingProvider().getTransactionManagerName();
              Object txMgr = ApplicationContext.getNamingProvider().lookup(null, jndiName, TransactionManager.class);
              transMgr = (TransactionManager)txMgr;
          } catch (Exception ex) {
              StandardLogger logger = LoggerUtil.getStandardLogger();
              logger.severeException(ex.getMessage(), ex);
          }
          return transMgr;
      }
docs: Returns transaction manager