// Calculate the waitInterval between periodic refreshes so that each server
	// independently picks a (uniformly distributed) random time in an interval
	// of size = baseInterval.
	//
	// For example:
	//
	//    - if baseInterval=10s, then 5s <= waitInterval() < 15s
	//
	//    - if baseInterval=10m, then 5m <= waitInterval() < 15m
	waitInterval := func() time.Duration {