archaius-core/src/main/java/com/netflix/config/ConcurrentCompositeConfiguration.java
@Override
    public boolean containsKey(String key)
    {
        if (overrideProperties.containsKey(key)) {
            return true;
        }
        for (Configuration config : configList)
        {
            if (config.containsKey(key))
            {
                return true;
            }
        }
        return false;
    }
@Override
    public boolean containsKey(String key)
    {
        if (overrideProperties.containsKey(key)) {
            return true;
        }
        for (Configuration config : configList)
        {
            if (config.containsKey(key))
            {
                return true;
            }
        }
        return false;
    }
Check if the any of the sub configurations contains the specified key.

@param key the key whose presence in this configuration is to be tested

@return <code>true</code> if the configuration contains a value for this
key, <code>false</code> otherwise