private void createDocprocMBusServersAndClients(ConfigModelRepo pc) {
        for (ContainerCluster<?> cluster: ContainerModel.containerClusters(pc)) {
            addServerAndClientsForChains(cluster.getDocproc());
        }
    }
Processing that requires access across different plugins

@param root root config producer
@param configModelRepo a {@link ConfigModelRepo}
config-model/src/main/java/com/yahoo/vespa/model/builder/xml/dom/VespaDomBuilder.java