private static final class ServiceManagerState {
    final Monitor monitor = new Monitor();

    @GuardedBy("monitor")
    final SetMultimap<State, Service> servicesByState =
        MultimapBuilder.enumKeys(State.class).linkedHashSetValues().build();

    @GuardedBy("monitor")
    final Multiset<State> states = servicesByState.keys();

    @GuardedBy("monitor")