@Override
        public long activate() {
            if (preparedHosts == null)
                prepare();
            if (failActivate)
                throw new IllegalStateException("failActivate is true");

            activations++;
            try (var lock = provisioner.lock(application.id)) {
                try (NestedTransaction t = new NestedTransaction()) {
                    provisioner.activate(preparedHosts, new ActivationContext(activations, false), new ApplicationTransaction(lock, t));
                    t.commit();
                    lastActivationTimes.put(application.id, clock.instant());
                }
            }
            return activations;
        }
The list of hosts prepared in this. Only set after prepare is called (and a provisioner is assigned)
node-repository/src/main/java/com/yahoo/vespa/hosted/provision/testutils/MockDeployer.java