Return a currently active transaction or create a new one.
ITransactionStatus representing the new or current transaction.
This implementation handles propagation behavior.
Note that parameters like isolation level or timeout will only be applied to new transactions, and thus be ignored when participating in active ones. Furthermore, they aren't supported by every transaction manager: a proper implementation should throw an exception when custom values that it doesn't support are specified.
|TransactionException||In case of lookup, creation, or system errors.|