void setGeneration(Long generation) {
        ConfigState<T> prev = config.get();
        this.config.set(new ConfigState<>(true, generation, prev.applyOnRestart(), prev.isConfigChanged(), prev.getConfig(), prev.payloadChecksums));
    }
Used by {@link FileConfigSubscription} and {@link ConfigSetSubscription}
config/src/main/java/com/yahoo/config/subscription/impl/ConfigSubscription.java