Pass element from option select populated from JSON to Controller

This my very first post, for several months I was able to find correct answer but this time I stuck.
I manage to create in JavaScript functions to create dependent - cascade drop-down-lists, when I choose Car Brand, then Models are served in next list and series in another accordingly.
But can not send the chosen positions to Java Controller. Im open to criticism :-) Ill be very grateful for any help.

So the view looks as follows:

<!-- language: lang-html -->

	<form  action=make method="POST">
		<div class="item">
			<h3 class="item-title">Choose car</h3>
			<span class="year"></span>
			<select id="name" name="name" class="wrapper"  onchange="populateSelectModel(), populateSelectSeries()">
                <option   value="">--Select--</option>
            </select>
			<select id="model" name="model" onchange="populateSelectSeries()" >
                 <option value="">--Select--</option>
             </select>
             <select id="seria" name="seria">
                  <option value="">--Select--</option>
             </select>

			<input type="hidden" th:name="${_csrf.parameterName}" th:value="${_csrf.token}"/>
			<button type="submit" class="btn-primary">Submit</button>
		</div>

	</form>

<!-- end snippet -->

<!-- begin snippet: js hide: false console: true babel: false -->

<!-- language: lang-js -->

var selectBrand = document.getElementById("name");
var selectModel = document.getElementById("model");
var selectSeries = document.getElementById("seria");
var ourData;
     var ourRequest = new XMLHttpRequest();
    ourRequest.open('GET', 'https://raw.githubusercontent.com/ahmetozalp/auto-cars-makes-models-types/master/cars.json');
    ourRequest.onload = function(){
      ourData = JSON.parse(ourRequest.responseText);
   
   var selectedBrand = populateSelectBrand(ourData);
   populateSelectModel();
   populateSelectSeries();
  };
    ourRequest.send();


     function populateSelectBrand(lista) {
       
         for (var i = 0; i < lista.length; i++) {
            
            selectBrand.innerHTML = selectBrand.innerHTML +
                '<option value="">' + lista[i].brand + '</option>';
           
        }
    }
    
  
    function populateSelectModel() {
        selectModel.innerHTML = '<option value="">Select model';
      
            var jakIndex = selectBrand.selectedIndex - 1;  
            var howlong = ourData[jakIndex].models.length;
                    
           for (var i = 0; i < howlong; i++) {
    
    
        selectModel.innerHTML = selectModel.innerHTML +
            '<option value="">' + ourData[jakIndex].models[i].title + '</option>';       
            }
           
        }

    function populateSelectSeries() {
            selectSeries.innerHTML = '<option value="">Select series';
          
                var jakiIndex = selectBrand.selectedIndex -1 ;  
                var jakiIndexModelu = selectModel.selectedIndex-1;
                var howlong1 = ourData[jakiIndex].models[jakiIndexModelu].types;
                             
               for (var i = 0; i < howlong1.length; i++) { 
                   
                
                selectSeries.innerHTML = selectSeries.innerHTML +
                '<option value="">' + ourData[jakiIndex].models[jakiIndexModelu].types[i] + '</option>';       
                }
              
            }

<!-- end snippet -->

==================================================================
Finally when I can get via Controller the selected values from "name","model","series" I`m getting empty Strings (not null)
Java Controller

@Controller

@RequestMapping("make")
public class MAkeController {

@PostMapping
public String downloadMake(String name, String model, String seria) throws IOException {
    return ("download");
}

}

screen shot from IntelliJ, while debugging

While populating the select drop-down options, you are setting option tag value as empty string value="" in all the three functions as below

<option value="">

You need to set the respective item in value attribute of option tag too.

For example, similar to below in populateSelectBrand function:

selectBrand.innerHTML = selectBrand.innerHTML + '<option value="' + lista[i].brand + '">' + lista[i].brand + '</option>';

Do the same in other functions too.

When you do form submit, the selected option value will be sent to the server not the label displaying in thr UI screen.