@Override
    protected ProcessingChainsBuilder readChains(DeployState deployState, TreeConfigProducer<AnyConfigProducer> ancestor, List<Element> processingChainsElements,
                                                 Map<String, ComponentsBuilder.ComponentType<?>> outerComponentTypeByComponentName) {
        return new ProcessingChainsBuilder(deployState, ancestor, processingChainsElements, outerComponentTypeByComponentName);
    }
Root builder of the processing model

@author  bratseth
config-model/src/main/java/com/yahoo/vespa/model/builder/xml/dom/chains/processing/DomProcessingBuilder.java