private static boolean containsIndexingChain(ComponentRegistry<DocprocChain> allChains, ChainSpecification chainSpec) {
        if (IndexingDocprocChain.NAME.equals(chainSpec.componentId.stringValue())) return true;

        ChainSpecification.Inheritance inheritance = chainSpec.inheritance;
        for (ComponentSpecification parentComponentSpec : inheritance.chainSpecifications) {
            ChainSpecification parentSpec = getChainSpec(allChains, parentComponentSpec);
            if (containsIndexingChain(allChains, parentSpec)) return true;
        }

        return false;
    }
Returns indexing cluster implicitly created by this,
or empty if an explicit cluster is used (or if called before the build phase)
config-model/src/main/java/com/yahoo/vespa/model/content/Content.java