archaius-core/src/main/java/com/netflix/config/ConcurrentCompositeConfiguration.java
public void addConfigurationAtIndex(AbstractConfiguration config, String name, int index) 
    throws IndexOutOfBoundsException {
        if (!configList.contains(config)) {
            checkIndex(index);
            configList.add(index, config);
            if (name != null) {
                namedConfigurations.put(name, config);
            }
            config.addConfigurationListener(eventPropagater);
            fireEvent(EVENT_CONFIGURATION_SOURCE_CHANGED, null, null, false);
        } else {
            logger.warn(config + " is not added as it already exits");
        }
    }
public void addConfigurationAtIndex(AbstractConfiguration config, String name, int index) 
    throws IndexOutOfBoundsException {
        if (!configList.contains(config)) {
            checkIndex(index);
            configList.add(index, config);
            if (name != null) {
                namedConfigurations.put(name, config);
            }
            config.addConfigurationListener(eventPropagater);
            fireEvent(EVENT_CONFIGURATION_SOURCE_CHANGED, null, null, false);
        } else {
            logger.warn(config + " is not added as it already exits");
        }
    }
Add a configuration with a name at a particular index.

@throws IndexOutOfBoundsException