public void addComponent(ComponentId id, CHILD producer) {
        CHILD existing = producerById.put(id, producer);
        if ( existing != null) {
            throw new IllegalArgumentException("Both " + producer + " and " + existing + " are configured" +
                                               " with the id '" + id + "'. All components must have a unique id.");
        }
        addChild(producer);
    }
A group of config producers that have a component id.

@author Tony Vaagenes
config-model/src/main/java/com/yahoo/vespa/model/container/component/ConfigProducerGroup.java