Using a instance method as a proxy to the real method we can fake it to avoid calling the real method

TestableDependency.java

    // this method is fakable
    public String getTranslation(String key, Locale locale) {
        return getTranslationOld(key, locale);
    }

    /**
     * @deprecated use instance method instead
     */
    public static String getTranslationOld(String key, Locale locale) {
        Object keys = getTranslationMap().get(locale.toString());
        // logic ...
        // etc ...
        
        return null;
    }