public ApplicationReindexing withSpeed(String cluster, String documentType, double speed) {
        Cluster current = clusters.get(cluster);
        if (current == null) throw new IllegalArgumentException("no existing reindexing for cluster '" + cluster + "'");
        Status status = current.ready.get(documentType);
        if (status == null) throw new IllegalArgumentException("no existing reindexing for document type '" + documentType + "' in cluster '" + cluster + "'");
        Cluster modified = new Cluster(current.pending,
                                       with(documentType, new Status(status.ready(), speed, status.cause()), current.ready));
        return new ApplicationReindexing(enabled, with(cluster, modified, clusters));
    }
Returns a copy of this with updated speed for the given document type in the given cluster.
configserver/src/main/java/com/yahoo/vespa/config/server/application/ApplicationReindexing.java