JSON schema using Java objects

Question

I have this JSON schema:

 {  
   "name":{  
      "first":{  
     "attributeValue":"firstName",
     "attributeType":1,
     "dataType":1
      },
      "last":{  
     "attributeValue":"lastName",
     "attributeType":1,
     "dataType":1
      }
   },
   "age":{  
      "attributeValue":"age",
      "attributeType":1,
      "dataType":2
   },
   "address":{  
      "number":{  
     "attributeValue":"number",
     "attributeType":1,
     "dataType":1
      },
      "street":{  
     "attributeValue":"street",
     "attributeType":1,
     "dataType":1
      },
      "city":{  
     "attributeValue":"city",
     "attributeType":1,
     "dataType":1
      },
      "country":{  
     "attributeValue":"country",
     "attributeType":1,
     "dataType":1
      }
   },
   "fullName":{  
      "attributeValue":"#firstName.concat(' ').concat(#lastName)",
      "attributeType":2,
      "dataType":1
   }
}

In here, each node that has attributeValue, dataType and attributeType nodes are called Field. Every other parent node is a handler. "name" is a handler which has "first" and "last" fields. But for age, since there is no parent key, there should be a handler created named "age" and a field "age" should be added to that. Handlers can have handlers. Handlers have fields in them.

Here is the Handler object representation:

  public interface Handler<T> {
     void addField(Field field);
    void addHandler(Handler handler);
     String getName();
     List<Field> getFields();
     T handle(T target);
  }

Here is the field representation:

  public interface Field<T> {
      void setValue(String value);
      T getField();
     String getFieldName();
  }

Now I need to parse the json schema and return a list of handlers:

   private List<Handler> parseJsonSchema(Handler handler, String jsonSchema) throws JSONMapperException {
    List<Handler> handlerList = new ArrayList<>();
    boolean isParentLeaf = false;
    Field<ObjectNode> objectNodeField = null;
    try {
        JsonNode rootNode = objectMapper.readTree(jsonSchema);
        Iterator<Map.Entry<String, JsonNode>> childrenIterator = rootNode.fields();
        while (childrenIterator.hasNext()) {
        Map.Entry<String, JsonNode> field = childrenIterator.next();
        System.out.println("Key: " + field.getKey() + "\tValue:" + field.getValue());
        if (field.getValue().has("attributeValue") && field.getValue().has("attributeType")
                && field.getValue().has("dataType")) {
            if (handler == null) {
                handler = jsonNodeHandlerFactory.create(field.getKey());
                isParentLeaf = true;
            }
            JsonNode valueNode = field.getValue();
            //String fieldName = valueNode.get("attributeValue").toString();
            String fieldName = field.getKey();
            String dataType = valueNode.get("dataType").toString();
            switch (dataType) {
                case "1":
                    objectNodeField = dataFieldFactory.createStringField(fieldName);
                    break;
                case "2":
                    objectNodeField = dataFieldFactory.createIntField(fieldName);
                    break;
                case "3":
                    objectNodeField = dataFieldFactory.createBooleanField(fieldName);
                    break;
                default:
                    break;
            }
            handler.addField(objectNodeField);
            if(isParentLeaf) {
                handlerList.add(handler);
                handler =null;
            }
        } else {
            handler = jsonNodeHandlerFactory.create(field.getKey());
            List<Handler> handlers = parseJsonSchema(handler, field.getValue().toString());
            for (Handler handler1 : handlers) {
                if(handler != null) { //means we already have a handler and we've come into another handler
                    handler.addHandler(handler1);
                    handlerList.add(handler);
                } else {
                    handlerList.add(handler1);
                }
            }
            handler = null;
        }
        if ((handler != null && handler.getFields().size() == rootNode.size())) {
            handlerList.add(handler);
        }
        }
    } catch (IOException e) {
        logger.error(JSON_SCHEMA_PARSE_EXCEPTION, e);
        throw new JSONMapperException(JSON_SCHEMA_PARSE_EXCEPTION);
    }
    return handlerList;
    }

But it overrides handlers, when there are handlers within handlers. Also, it looks pretty clumsy with too many null assignments and if checks. Is there a better way to do what this method is already doing? That is, return the schema as a list of handlers.