Read from json and write back while preserving original formatting in java

I am trying to read a json file and update a specific field. I am able to get to the proper nested location, but when I save it back after update, I get lots of "rn" instead of the original formatting.
I have tried using two approaches for reading:

   private LinkedHashMap get3rdJsonAsMap() {
        objectMapper = new ObjectMapper();//.enable(SerializationFeature.INDENT_OUTPUT);
        LinkedHashMap json = null;
        try {
            json = (LinkedHashMap)objectMapper.readValue(new File(this.mono3rdJsonPath), Object.class);
        } catch (IOException e) {
            e.printStackTrace();
        }
        return json;
    }

and with:

  private JsonNode get3rdJsonAsNode() {
    objectMapper = new ObjectMapper();//.enable(SerializationFeature.INDENT_OUTPUT);
    JsonNode json = null;
    try {
        json = objectMapper.readTree(new File(this.mono3rdJsonPath));
    } catch (IOException e) {
        e.printStackTrace();
    }
    return json;
}

I am writing with this:

 private void writeProvisionAsObject(Object json) {
        ObjectWriter writer = objectMapper.writerWithDefaultPrettyPrinter();
        String updatedJsonString;
        try {
            updatedJsonString = writer.writeValueAsString(json);
            // Write the updated JSON string back to the JSON file
            objectMapper.writeValue(new File(this.filePath), updatedJsonString);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

Also I’ve heard of JsonTokenizer but I’ve read that in order to preserve original formatting, I must append each line manually, which I am trying to avoid.

How can I achieve preserving orginal formating?