if(sequencingCallback == null) {
sequencingCallback = sequencingCallbackFactory.createSequencingCallback();
}
return sequencingCallback;
} else if(getTransactionController().numSessionsRequiringSequencingCallback() > 1) {
SequencingCallback callback = null;
if(sequencingCallbackMap == null) {
sequencingCallbackMap = new HashMap(getTransactionController().numSessionsRequiringSequencingCallback());
} else {
callback = sequencingCallbackMap.get(dbSession);
}