Convert a multi layer json into a single layer json in java 8

Question

I am trying to organize a complex json config file with multiple layers so that it can be easily read in code.

So I want to convert something like this:

{
  "rootProp": {
    "a": 1,
    "moreObj": {
      "b": "beta"
    }
  }
}

into

{
  "rootProp.a": 1,
  "rootProp.moreObj.b": "beta"
}

I have a recursive version, but I'm curious if this can be done with streams or with some library.

public JsonObject flattenJson(JsonObject jsonObject) {
    return flattenJson(jsonObject, "");
}

public JsonObject flattenJson(JsonObject jsonObject, String prefix) {
    JsonObject result = new JsonObject();

    jsonObject
            .forEach(entry -> {
                if (entry.getValue() instanceof JsonArray) {
                    throw new RuntimeException("Config shouldn't contain arrays");
                }
                if (entry.getValue() instanceof JsonObject) {
                    JsonObject value = (JsonObject) entry.getValue();
                    JsonObject flat = flattenJson(value, entry.getKey() + ".");
                    flat
                            .stream()
                            .forEach(flattenedEntry -> {
                                String key = prefix + flattenedEntry.getKey();
                                result.put(key, flattenedEntry.getValue());
                            });
                } else {
                    String keyName = prefix + entry.getKey();
                    result.put(keyName, entry.getValue());
                }
            });
    return result;
}