@Override
    public String toString() {
        if (cachedToString == null) {
            String newToString = generateToString();
            cachedToString = newToString;
            return newToString;
        }
        return cachedToString;
    }
Store the default value for key while giving precedence to default values in the property resolver
ribbon-core/src/main/java/com/netflix/client/config/ReloadableClientConfig.java