@Override
    public <T> Optional<T> getIfSet(IClientConfigKey<T> key) {
        return (Optional<T>)internalProperties.getOrDefault(key, Optional.empty());
    }
Resolve a property's final value from the property value.
- client scope
- default scope
ribbon-core/src/main/java/com/netflix/client/config/ReloadableClientConfig.java