How to send list of class objects as a body parameter.

[fidahussain2356]

Below is my code.
AndroidNetworking.post("http://"+ Login.ip+"/api/teachers/test_courses")
.addBodyParameter(added_courses_list)
.setTag("test")
.setPriority(Priority.IMMEDIATE)
.build()
.getAsString(new StringRequestListener() {
@OverRide
public void onResponse(String response) {

                    Log.i("success",response);
                }

                @Override
                public void onError(ANError anError) {

                    Log.i("Error code", String.valueOf(anError.getErrorCode()));
                    Log.i("Error Detail",anError.getErrorDetail());
                    Log.i("Error Body",anError.getErrorBody());
                }
            });

and this is code of web api.

    [HttpPost]
    [Route("test_courses")]

    public HttpResponseMessage test_courses([FromBody] List<model_teacher_add_courses> obj)
    {
        HttpResponseMessage message = null;
        if (obj == null)
        {
            message = Request.CreateResponse("Its null.");
        }
        else
        {
            model_teacher_add_courses m = new model_teacher_add_courses();
           
            message = Request.CreateResponse(obj);
        }

return message;
}

when i run this code "its null" is returned. i think list is not reaching to web api.
Kindly help me.