How to add another List of item for DropDownMenu, and then use the items in widget

So I'm trying to make a drop down menu for each options and insert a different List of items each. First of all, because my Dropdownmenu widget shares the same properties for one and another, I extracted the widget to another class name "MenuDropDown". Here is the code for the widget.

import 'package:flutter/material.dart';
import 'List.dart';

class MenuDropDown extends StatefulWidget {
  final String dropdownText;
  final List<DropdownMenuItem<String>> itemList;
  MenuDropDown({this.dropdownText, this.itemList});
  @override
  _MenuDropDownState createState() => _MenuDropDownState();
}

class _MenuDropDownState extends State<MenuDropDown> {
  String selectedItem;

  List<DropdownMenuItem> getGroomingTypeList() {
    List<DropdownMenuItem<String>> dropdownItems = [];
    for (String groomingType in groomingTypeList) {
      var newItem = DropdownMenuItem(
        child: Text(groomingType),
        value: groomingType,
      );
      dropdownItems.add(newItem);
    }
    return dropdownItems;
  }

  List<DropdownMenuItem> getCatBreedsList() {
    List<DropdownMenuItem<String>> dropdownItems = [];
    for (String catBreed in catBreedsList) {
      var newItem = DropdownMenuItem(
        child: Text(catBreed),
        value: catBreed,
      );
      dropdownItems.add(newItem);
    }
    return dropdownItems;
  }

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.fromLTRB(0, 8.0, 0, 10.0),
      child: Container(
        width: 325.0,
        height: 50.0,
        decoration: BoxDecoration(
          boxShadow: [
            BoxShadow(
              color: Colors.black45,
              offset: Offset(2.5, 5.5),
              blurRadius: 5.0,
            )
          ],
          borderRadius: BorderRadius.circular(8),
          color: Colors.white,
        ),
        child: DropdownButtonHideUnderline(
          child: DropdownButton(
              value: selectedItem,
              hint: Padding(
                padding: const EdgeInsets.fromLTRB(22.0, 0, 0, 0),
                child: Text(
                  widget.dropdownText,
                  style: TextStyle(),
                ),
              ),
              items: widget.itemList,
              onChanged: (value) {
                setState(() {
                  selectedItem = value;
                });
              }),
        ),
      ),
    );
  }
}

above here I created a method to get the list item from the list class that I already created, First it works if I hardcoded the method into the Dropdownmenu's items properties to show the item list, but because I need to use the different list for the different widget, so I think if I try to create a variable of List named itemList, so I can access it from the other class where I can call just the customized variable.

And this is the Stateful widget where i use my Extracted Dropdownmenu widget :

import 'package:flutter/material.dart';
import 'TitleName.dart';
import 'dropdownmenu.dart';

class InformationDetail extends StatefulWidget {
  @override
  _InformationDetailState createState() => _InformationDetailState();
}

class _InformationDetailState extends State<InformationDetail> {
  MenuDropDown _menuDropDown = MenuDropDown();
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SafeArea(
        child: Container(
          child: Column(
            children: <Widget>[
              Container(
                margin: EdgeInsets.fromLTRB(25.0, 68.0, 70.0, 26.0),
                child: Text(
                  'Information Detail',
                  style: TextStyle(fontSize: 35.0),
                ),
              ),
              Column(
                // Wrap Column
                children: <Widget>[
                  Column(
                    children: <Widget>[
                      TitleName(
                        titleText: 'Grooming Type',
                        infoIcon: Icons.info,
                      ),
                      MenuDropDown(
                        dropdownText: 'Grooming Type...',
                      //I'm trying to implement the list here with a custom variable that contain 
                        a method with different list in dropdownmenu class
                      itemlist: getGroomingTypeList(),
                      ),
                      TitleName(
                        titleText: 'Cat Breeds',
                      ),
                      MenuDropDown(
                        dropdownText: 'Cat Breeds...',
                      ),
                      TitleName(
                        titleText: 'Cat Size',
                        infoIcon: Icons.info,
                      ),
                      MenuDropDown(
                        dropdownText: 'Cat Size...',
                      ),
                      TitleName(
                        titleText: 'Add-On Services',
                      ),
                      MenuDropDown(
                        dropdownText: 'Add - On Services...',
                      ),
                      Container(
                        margin: EdgeInsets.fromLTRB(0, 15.0, 0, 0),
                        width: 75.0,
                        decoration: BoxDecoration(
                          color: Colors.white,
                          shape: BoxShape.rectangle,
                          border: Border.all(
                            color: Colors.black,
                          ),
                          borderRadius: BorderRadius.circular(12.0),
                        ),
                        child: IconButton(
                          icon: Icon(Icons.arrow_forward),
                          onPressed: () {
                            Navigator.of(context)
                                .pushNamed('/ReservationDetail');
                          },
                        ),
                      ),
                    ],
                  ),
                ],
              ),
            ],
          ),
        ),
      ),
    );
  }
}

And this is the list that I want to use for each of dropdown menu widget

const List groomingTypeList = ['Basic Grooming', 'Full Grooming'];

const List catBreedsList = [
  'Persia',
  'Anggora',
  'Domestic',
  'Maine Coon',
  'Russian Blue',
  'Slamese',
  'Munchkin',
  'Ragdoll',
  'Scottish Fold',
];

const List catSizeList = [
  'Small Size',
  'Medium Size',
  'Large Size',
  'Extra Large Size',
];

const List addOnServicesList = [
  'Spa & Massage',
  'Shaving Hair / Styling',
  'Injection Vitamis Skin & Coat',
  'Cleaning Pet House and Environment',
  'Fur Tangled Treatment',
];

I got stuck from there. How to use a different list for each dropdown menu widget that I made, because I already tried to make a constructor, variable, and method so I can use it separately, but instead I got an error that says,

type 'List' is not a subtype of type 'List<DropdownMenuItem>'

I think I implemented it in the wrong way in the first place. I really need help with another solution to these problems. thank you, everyone!