UserTask add formFields for ModelInstance

Hello,

I’m trying to create a new UserTask Model Instance to return that xml for client.

When I run this code, it give me userTask model with Id, Name and FormKey in xml.
But I want to add FormFields at here.
I was trying to setCamundaFormHandlerClass but it doesnt set formFields in modelInstance.
What should I do for add formFields at here?

My Code;

UserTask task = createElement(modelInstance, process, “task”, “GeneralUserTaskModel”, UserTask.class, plane, 50d, 50d, 75d, 100d, true);
task.setName(“example”);
task.setCamundaFormKey(“exampleFormKey”);
task.setCamundaFormHandlerClass(UserTaskFormFieldDto.class.getName());

Thank you!