code: private void setClusterSize(String clusterName, int newSize)
        throws InterruptedException {
      Preconditions.checkArgument(newSize > 0, "Cluster size must be > 0");
      logger.info("Updating cluster %s to size %d", clusterName, newSize);
      Operation operation = client.updateCluster(Cluster.newBuilder()
          .setName(clusterName)
          .setServeNodes(newSize)
          .build());
      waitForOperation(operation.getName(), 60);
      logger.info("Done updating cluster %s.", clusterName);
    }
docs: Update a specific cluster's server node count to the number specified