s.updateLock.Lock()
	defer s.updateLock.Unlock()

	seenBefore := s.sourcesSeen.Has(source)
	adds, updates, deletes, removes, reconciles := s.merge(source, change)
	firstSet := !seenBefore && s.sourcesSeen.Has(source)

	// deliver update notifications
	switch s.mode {
	case PodConfigNotificationIncremental:
		if len(removes.Pods) > 0 {
			s.updates <- *removes
		}

        List<T> result = new ArrayList<T>();
        Iterator<? extends Collection<T>> iterator = availableValuesByDescriptor.iterator();
        if (iterator.hasNext()) {
            Collection<T> firstSet = iterator.next();
            result.addAll(firstSet);
            while (iterator.hasNext()) {
                Collection<T> next = iterator.next();
                result.retainAll(next);
            }
        }
        return result;

	// more than one of each per m, p, and goroutine.
	firstGen := traceNextGen(trace.lastNonZeroGen)

	// Reset GC sequencer.
	trace.seqGC = 1

	// Reset trace reader state.
	trace.headerWritten = false
	trace.readerGen.Store(firstGen)
	trace.flushedGen.Store(0)

	// Register some basic strings in the string tables.
	traceRegisterLabelsAndReasons(firstGen)

	// Stop the world.
	//