@Override
    protected DocprocChainsBuilder readChains(DeployState deployState, TreeConfigProducer<AnyConfigProducer> ancestor, List<Element> docprocChainsElements,
                                              Map<String, ComponentType<?>> outerComponentTypeByComponentName) {
        return new DocprocChainsBuilder(deployState, ancestor, docprocChainsElements, outerComponentTypeByComponentName);
    }
Builds the docproc chains model from xml.

@author gjoranv
config-model/src/main/java/com/yahoo/vespa/model/builder/xml/dom/chains/docproc/DomDocprocChainsBuilder.java