Openflow Transaction Manager wrapper does not handle synchronization properly

TransactionChainManager implementation uses synchronization to guarantee that clients are able to perform modifications and submit actions in a transaction chain that is unique at a given point of time. Also, the creation of the transaction chain is hidden and the transaction is created by the first client that tries to add a modification the first time or after a submit.

There are few bugs in the code of this class which above promise is not guaranteed.

• wTx variable does not handles the reference to the current transaction properly in all cases
• lifecycle is closed when an exception is returned by MD-SAL that commonly could happen
• synchronization is not implemented properly to guaranteed there is only one transaction open at a given point of time