updateCustomObject function
Returns updated object
className - name of the class of custom objects which you want to update
id - id of the object, you want to update
params - additional parameter for updating, see https://developers.connectycube.com/server/custom_objects?id=parameters-3
Implementation
Future<CubeCustomObject> updateCustomObject(
    String className, String id, Map<String, dynamic> params) {
  return UpdateCustomObjectQuery(className, id, params).perform();
}