private ApplicationConfigProducerRoot getVespa() {
        if (isRoot()) return null;
        if (isVespa()) {
            return (ApplicationConfigProducerRoot)this;
        } else {
            return getParent().getVespa();
        }
    }
Returns the {@link ApplicationConfigProducerRoot} that is the parent of this sub-tree, or null
if this sub-tree has no Vespa parent.
config-model/src/main/java/com/yahoo/config/model/producer/AnyConfigProducer.java