protected ClassLoader getConfigClassLoader(String producerName) {
        return findInheritedClassLoader(getClass(), producerName);
    }
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