allback function to be called when an event is sent from the
    Berkeley DB library.
    <p>
    This event callback is received when the replication manager did not
    receive enough acknowledgements (based on the acknowledgement policy
    configured with <A HREF="../../../com/sleepycat/db/EnvironmentConfig.html#setReplicationManagerAckPolicy(com.sleepycat.db.ReplicationManagerAckPolicy)"><CODE>EnvironmentConfig.setReplicationManagerAckPolicy</CODE></A>)
    to ensure a transaction's durability within t