code: public <R> R executeTransactionalCommand(final TransactionalCommand<R> command)
              throws MithraBusinessException
      {
          return this.executeTransactionalCommand(command, this.defaultTransactionStyle);
      }
docs: executes the transactional command. If the command throws an exception, the transaction is rolled back.
  If the exception is caused by a retriable condition (e.g. database deadlock), it is automatically
  retried (up to 10 times).
  @param command an implementation of TransactionalCommand
  @return whatever the transaction command's execute method returned.
  @throws MithraBusinessException