public Set<ApplicationId> applicationInstances(TenantName tenantName) {
        return toApplicationInstances(send(request(HttpRequest.newBuilder(applicationsPath(tenantName))
                                                              .timeout(Duration.ofSeconds(20)),
                                                   GET)),
                                      tenantName);
    }
Returns the application instances for the given tenant.
hosted-api/src/main/java/ai/vespa/hosted/api/ControllerHttpClient.java