public Optional<ApplicationData> applicationDataOldFormat(ApplicationId id) {
        Optional<byte[]> data = curator.getData(applicationPath(id));
        if (data.isEmpty() || data.get().length == 0) return Optional.empty();

        return Optional.of(new ApplicationData(id,
                                               OptionalLong.of(data.map(bytes -> Long.parseLong(Utf8.toString(bytes))).get()),
                                               OptionalLong.empty()));
    }
Returns application data for the given application.
Returns Optional.empty() if application not found or no application data exists.
configserver/src/main/java/com/yahoo/vespa/config/server/application/ApplicationCuratorDatabase.java