Retrofit Multiple Query Parameter with custom QueryMap .... Example: ?tag[5]=12&tag[20]=3&tag[11]=5

ApiEndpointInterface.java

public interface ApiEndpointInterface {

    //Example of the implementation 
    @FormUrlEncoded
    @POST("{token}/pay/cash?sandbox=1")
    Call<ResponseBody> orderProducts(@Path("token") String token,
                                     @QueryMap Map<String, String> map,
                                     @Field("address") String addressId);

}

RetrofitMapEntry.java

import java.util.List;
import java.util.Map;

/**
 * Created by Valdio Veliu on 10/6/2016.
 */

public class RetrofitMapEntry implements Map.Entry<List<String>, List<String>> {

    private List<String> key;
    private List<String> value;

    public RetrofitMapEntry(List<String> key, List<String> value) {
        this.key = key;
        this.value = value;
    }

    @Override
    public List<String> getKey() {
        return key;
    }

    @Override
    public List<String> getValue() {
        return value;
    }

    @Override
    public List<String> setValue(List<String> value) {
        return null;
    }
}

RetrofitQueryMapBuilder.java

import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map.Entry;

/**
 * Created by Valdio Veliu on 10/6/2016.
 */

public class RetrofitQueryMapBuilder {

    public LinkedHashMap<String, String> customHashMap(String queryKey, Entry<List<String>, List<String>> entry) {

        LinkedHashMap<String, String> map = new LinkedHashMap<>();
        String key = queryKey;
        List<String> keyList = entry.getKey();
        List<String> valueList = entry.getValue();
        //key and value lists must have the same length
        if (keyList == null || valueList == null) return null;
        if (keyList.size() != valueList.size()) return null;

        int listSize = valueList.size();
        for (int i = 0; i < listSize; i++) {
            map.put(key + "[" + keyList.get(i) + "]", valueList.get(i));
        }
        return map;
    }
}

SomeClass.java

public class SomeClass {

    //...
  
  
    private void makeNerworkCall() {
        Call<ResponseBody> networkCall =...;

        //Fill the Lists with some data
        //Their length should be the same
        List<String> keys = new ArrayList<>();
        List<String> values = new ArrayList<>();
        //... Fill with data
      
        //Build the LinkedHashMap
        String KEY_TAG = "tag"; //Specify the String TAG
        Map.Entry<List<String>, List<String>> entry = new RetrofitMapEntry(keys, values);
        LinkedHashMap<String, String> map = new RetrofitQueryMapBuilder().customHashMap(KEY_TAG, entry);

        networkCall = apiService.orderProducts("TOKEN_STRING", map, "addressId");
    }
}

what if i need to send my parameter is Example: ?tag[5]=12,45,34 ?