Android代码发送的数据由C＃webservice接收为null

Question

我使用volley将JSON对象从android代码发送到C＃webservice。以下是Android代码：

    List<JSONObject > items = new ArrayList<JSONObject>();  
    JSONObject field = new JSONObject();

    String base64String = Base64.encodeToString(image_in_byte, Base64.DEFAULT);
    String file_str = file.getName();
    SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy HH:mm:ss.SS");
    String dateFormat = sdf.format(date);

    field.put("ID", file_str);
    field.put("IsTemp", "true");
    field.put("Image", base64String);
    field.put("Type", "JPEG" );
    items.add(field);

    JSONObject temp = new JSONObject();
            temp.put("field1", "data1");
            temp.put("field2", "data2");
            temp.put("Input1", items);
            temp.put("field3", dateFormat);
            temp.put("field4", "test");
            temp.put("field5", dateFormat);
            temp.put("field6", "test");

       try
            {
            String SERVER = "http:// webservice url";
            JsonObjectRequest jsObjRequest = new
            JsonObjectRequest(Request.Method.POST,SERVER,temp, 
                    new Response.Listener<JSONObject>()
                    {
                        @Override
                        public void onResponse(JSONObject response) {
                            System.out.println(response);
                            //hideProgressDialog();
                        }
                    },
                    new Response.ErrorListener()
                    {
                        @Override
                        public void onErrorResponse(VolleyError error)
                        {
                            Toast.makeText(getApplicationContext(), 
                          error.toString(), Toast.LENGTH_SHORT).show();
                        }
                    });

            queue.add(jsObjRequest);
            }
            catch(Exception ex)
            {
                ex.printStackTrace();
            }

以下是C＃webservice

    [AllowAnonymous]
    [Route("webservice")]
    [HttpPost]
    public async Task<IHttpActionResult> UploadData(Data F_Data)
    {
        if (F_Data == null ||F_Data.Input1 == null)
        {
            return BadRequest("Input parameter is empty");
        }            
    }


   public class Input_F
   {
    public int ID { get; set; }
    public bool IsTemp { get; set; }
    public string Image { get; set; }
    public string Type { get; set; }
   }

  public class Data
  {
    public string field1 { get; set; }
    public string field2 { get; set; }
    public List<Input_F> Input1{ get; set; }
    public DateTime field3 { get; set; }
    public string field4 { get; set; }
    public DateTime field5{ get; set; }
    public string field6 { get; set; }

    }

在UploadData例程中，我将F_Data.Input1作为null。我能够获得Data类的其余字段，但是Input1为null。我不确定我是否正确地从我的Android代码发送Input1，任何指针都会有很大的帮助。