public HealthCheckService build() {
        checkState(startHealthy || updateHandler != null,
                   "Healthiness must be updatable by server listener or update handler.");
        return new HealthCheckService(healthCheckers.build(),
                                      healthyResponse, unhealthyResponse,
                                      maxLongPollingTimeoutMillis, longPollingTimeoutJitterRate,
                                      pingIntervalMillis, updateHandler, updateListenersBuilder.build(),
                                      startHealthy, transientServiceOptionsBuilder.build());
    }
Returns a newly created {@link HealthCheckService} built from the properties specified so far.
core/src/main/java/com/linecorp/armeria/server/healthcheck/HealthCheckServiceBuilder.java