public List<Node> parkRecursively(String hostname, Agent agent, boolean forceDeprovision, String reason) {
        return moveRecursively(hostname, Node.State.parked, agent, forceDeprovision, Optional.of(reason));
    }
Parks all the nodes that are children of hostname before finally parking the hostname itself.

@return List of all the parked nodes in their new state
node-repository/src/main/java/com/yahoo/vespa/hosted/provision/node/Nodes.java