@Override
    public Optional<Instant> deployTime(ApplicationId application) {
        return Optional.ofNullable(lastPrepareTimes.get(application));
    }
Create a mock deployer which contains a substitute for an application repository, filled to
be able to call provision with the right parameters.
node-repository/src/main/java/com/yahoo/vespa/hosted/provision/testutils/MockDeployer.java