Delivery del = distributor.handle(null, ref, null);
assertNotNull(del);
checkReceiverGotRef(receivers, 0);
resetReceivers(receivers);
del = distributor.handle(null, ref, null);
assertNotNull(del);
checkReceiverGotRef(receivers, 1);
resetReceivers(receivers);
del = distributor.handle(null, ref, null);