private Optional<Deployment> tryDeployment(Optional<Mutex> lock,
                                               ApplicationId application,
                                               Deployer deployer,
                                               NodeRepository nodeRepository) {
        if (lock.isEmpty()) return Optional.empty();
        if (nodeRepository.nodes().list(Node.State.active).owner(application).isEmpty()) return Optional.empty();
        return deployer.deployFromLocalActive(application);
    }
Attempts to activate this deployment

@return the application config generation resulting from this deployment, or empty if it was not successful
node-repository/src/main/java/com/yahoo/vespa/hosted/provision/maintenance/MaintenanceDeployment.java