private static void notifyReplicatorStatusListener(final Replicator replicator, final ReplicatorEvent event,
        final Status status) {
      notifyReplicatorStatusListener(replicator, event, status, null);
    }
Called when the replicator state is changed. See {@link ReplicatorState}
@param peer the replicator's peer id.
@param newState the new replicator state.
@since 1.3.6
jraft-core/src/main/java/com/alipay/sofa/jraft/core/Replicator.java