org.datanucleus.TransactionImpl only uses ObjectManager to print debug messages.
It needes the OMFContext and the StoreManager
The new constructor should be like the below, where the key is a value used to print messages or raise exceptions with this key object refered.
public TransactionImpl(OMFContext omfContext, StoreManager storeManager, Object key)
The ObjectManager operations such as preCommit are replaced by TransactionListener