// to synthesize an artificial key and do a sort of 2-part
	// associative entity.
	type keyString string
	keyToAddrReadyMap := map[keyString]addressSet{}
	addrReadyMapKeyToPorts := map[keyString][]v1.EndpointPort{}
	for port, addrs := range portToAddrReadyMap {
		key := keyString(hashAddresses(addrs))
		keyToAddrReadyMap[key] = addrs
		if port.Port > 0 { // avoid sentinels