Statemachine core 4.0.0 ( Executing eventNotAccepted method)

[subratadey03]

We upgraded spring core to 4.0.0 version. As per our implementation we have extended StateMachineListenerAdapter<S, E> and overridden eventNotAccepted method like below :

@Override
public void eventNotAccepted(Message<E> event) {
    logger.warn(log, "eventNotAccepted", LogMessage.EVENT_NOT_ACCEPTED , event.getPayload());
} 

We observed, on every event we are getting above warning message, that means eventNotAccepted method is executing by the statemachine framework. But, there is no issue state transition for any event even though eventNotAccepted warning.

In older version 2.2.0 we had this method, but this method never executed.
Could you tell us , is it a bug in statemachine 4.0.0 or do we need to handle some other way ?

We debugged a lot but did not find any clue.
Please help us. we need urgent help on this.