class CloudJobConfigurationService {

    public Collection<CloudJobConfiguration> loadAll() {
        if (!regCenter.isExisted(CloudJobConfigurationNode.ROOT)) {
            return Collections.emptyList();
        }
        List<String> jobNames = regCenter.getChildrenKeys(CloudJobConfigurationNode.ROOT);
        Collection<CloudJobConfiguration> result = new ArrayList<>(jobNames.size());
        for (String each : jobNames) {
            Optional<CloudJobConfiguration> config = load(each);
            if (config.isPresent()) {
                result.add(config.get());
            }
        }
        return result;
    }

}