public AllClustersBucketSpacesConfig.Cluster.Builder clusterBucketSpaceConfigBuilder() {
        AllClustersBucketSpacesConfig.Cluster.Builder builder = new AllClustersBucketSpacesConfig.Cluster.Builder();
        for (NewDocumentType docType : getDocumentDefinitions().values()) {
            AllClustersBucketSpacesConfig.Cluster.DocumentType.Builder typeBuilder = new AllClustersBucketSpacesConfig.Cluster.DocumentType.Builder();
            typeBuilder.bucketSpace(bucketSpaceOfDocumentType(docType));
            builder.documentType(docType.getName(), typeBuilder);
        }
        return builder;
    }
Returns the distribution bits this cluster should use.
On Hosted Vespa this is hardcoded and not computed from the nodes because reducing the number of nodes is a common
operation, while reducing the number of distribution bits can lead to consistency problems.
This hardcoded value should work fine from 1-200 nodes. Those who have more will need to set this value
in config and not remove it again if they reduce the node count.
config-model/src/main/java/com/yahoo/vespa/model/content/cluster/ContentCluster.java