code: public void commit() throws HeuristicRollbackException, RollbackException, HeuristicMixedException, SystemException {
          Transaction transaction = currentTransaction();
          if (transaction == null) {
              throw new IllegalStateException("No active transaction");
          }
          transaction.commit();     
      }
docs: Commits the current transaction, if one exists.
  
  @throws IllegalStateException If the calling thread is not associated with a transaction.
  @throws SystemException If the transaction service fails in an unexpected way.
  @throws HeuristicMixedException If a heuristic decision was made and some some parts of the transaction have been
  committed while other parts have been rolled back.
  @throws HeuristicRollbackException If a heuristic decision to roll back the transaction was made.