default List<NodeTimeseries> getNodeTimeseries(Duration period, NodeList nodes) {
        return getNodeTimeseries(period, nodes.hostnames());
    }
Returns a list with one entry for each hostname containing
the snapshots recorded after the given time (or an empty snapshot if none).

@param period the duration into the past to return data for
@param hostnames the host names to return timeseries for, or empty to return for all hostnames
node-repository/src/main/java/com/yahoo/vespa/hosted/provision/autoscale/MetricsDb.java