The following solution parses a javax.json.JsonObject into a JSON string and then parses the JSON string into a com.fasterxml.jackson.databind.JsonNode using Jackson's ObjectMapper:

public JsonNode toJsonNode(JsonObject jsonObject) {

    // Parse a JsonObject into a JSON string
    StringWriter stringWriter = new StringWriter();
    try (JsonWriter jsonWriter = Json.createWriter(stringWriter)) {
        jsonWriter.writeObject(jsonObject);
    }
    String json = stringWriter.toString();

    // Parse a JSON string into a JsonNode
    ObjectMapper objectMapper = new ObjectMapper();
    JsonNode jsonNode = objectMapper.readTree(json);

    return jsonNode;
}

Right now, you are serializing your Pojo to a String, then parsing that String and converting it into a HashMap style object in the form of JSONObject.

This is very inefficient and doesn't accomplish anything of benefit.

Jackson already provides an ObjectNode class for interacting with your Pojo as a JSON object. So just convert your object to an ObjectNode. Here's a working example

Copypublic class Example {
    public static void main(String[] args) throws Exception {
        Pojo pojo = new Pojo();
        pojo.setAge(42);
        pojo.setName("Sotirios");
        ObjectMapper mapper = new ObjectMapper();
        ObjectNode node = mapper.valueToTree(pojo);
        System.out.println(node);
    }
}

class Pojo {
    private String name;
    private int age;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }
}

Otherwise, the way you are doing it is fine.

You need to use an ObjectMapper:

ObjectMapper mapper = new ObjectMapper();
JsonFactory factory = mapper.getJsonFactory(); // since 2.1 use mapper.getFactory() instead
JsonParser jp = factory.createJsonParser("{\"k1\":\"v1\"}");
JsonNode actualObj = mapper.readTree(jp);

Further documentation about creating parsers can be found here.