private static void addChainHop(RoutingTableSpec table, String configId, DocprocChain chain) {
        StringBuilder selector = new StringBuilder();
        selector.append("[LoadBalancer:cluster=").append(configId)
                .append(";session=").append(chain.getSessionName())
                .append("]");
        table.addHop(new HopSpec(chain.getServiceName(), selector.toString()));
    }
This function extrapolates any routes for the document protocol that it can from the vespa model.

@param plugins all initialized plugins of the vespa model
@return routing table for the document protocol
config-model/src/main/java/com/yahoo/vespa/model/routing/DocumentProtocol.java