archaius-core/src/main/java/com/netflix/config/ConcurrentCompositeConfiguration.java
@Override
    public Iterator<String> getKeys(String prefix)
    {
        Set<String> keys = new LinkedHashSet<String>();
        for (Iterator<String> it = overrideProperties.getKeys(prefix); it.hasNext();) {
            keys.add(it.next());
        }
        for (Configuration config : configList)
        {
            for (Iterator<String> it = config.getKeys(prefix); it.hasNext();)
            {
                keys.add(it.next());
            }
        }

        return keys.iterator();
    }
@Override
    public Iterator<String> getKeys(String prefix)
    {
        Set<String> keys = new LinkedHashSet<String>();
        for (Iterator<String> it = overrideProperties.getKeys(prefix); it.hasNext();) {
            keys.add(it.next());
        }
        for (Configuration config : configList)
        {
            for (Iterator<String> it = config.getKeys(prefix); it.hasNext();)
            {
                keys.add(it.next());
            }
        }

        return keys.iterator();
    }
Get the list of the keys contained in the sub configurations that match the
specified prefix.