@Override
    public ApplicationMutex lock(ApplicationId application) {
        return new ApplicationMutex(application, nodeRepository.applications().lock(application));
    }
Returns a list of nodes in the prepared or active state, matching the given constraints.
The nodes are ordered by increasing index number.
node-repository/src/main/java/com/yahoo/vespa/hosted/provision/provisioning/NodeRepositoryProvisioner.java