public JsonElement serialize(Memory src, Type typeOfSrc, JsonSerializationContext context) {
        return convert(src, new HashSet<Integer>(), true);
    }
Finds first occurrence of unicode character and returns its index or {@code -1} otherwise.
exts/jphp-json-ext/src/main/java/org/develnext/jphp/json/gson/MemorySerializer.java