@Override
    public Set<TransientServiceOption> transientServiceOptions() {
        return transientServiceOptions;
    }
Extends the request timeout by the specified {@code longPollingTimeoutMillis}, because otherwise
the client will get {@code "503 Service Unavailable} due to a {@link RequestTimeoutException} before
long-polling finishes.
core/src/main/java/com/linecorp/armeria/server/healthcheck/HealthCheckService.java