Unable to change the suggestions of AutoCompleteTextField - flutter

Question

Problem Description -
I am writing a search widget which is an AutoCompletTextField. It takes the queryString entered by the user and fetches related suggestions from the internet and then attaches those suggestions to the AutoCompleteTextField. Everything till fetching the suggestions from the internet is working just fine. The suggestions are not popping up when I call the setState() method of the widget. The suggestions don't pop up even after the call to setState(). Please help.
Code -
`import 'package:flutter/material.dart';
import 'miscellaneous_widgets.dart';
import 'models/AppContextData.dart';
import 'package:autocomplete_textfield/autocomplete_textfield.dart';
import 'workers/MCAutoSuggestionsGetter.dart';`
class CompanySearchBox extends StatefulWidget {
#override
_CompanySearchBoxState createState() => _CompanySearchBoxState();
}
class _CompanySearchBoxState extends State<CompanySearchBox> {
GlobalKey<AutoCompleteTextFieldState<String>> key =
GlobalKey<AutoCompleteTextFieldState<String>>();
List<String> lstSuggestions = List<String>();
TextEditingController companySearchBoxController = TextEditingController();
#override
Widget build(BuildContext context) {
AutoCompleteTextField<String> myCompanySearchBox;
TextEditingController CompanyNameController = TextEditingController();
myCompanySearchBox = AutoCompleteTextField<String>(
key: key,
clearOnSubmit: false,
style: TextFieldStyle.get(),
decoration: InputDecoration(
labelText: "Search companies here.",
//border: OutlineInputBorder(),
suffixIcon: Icon(Icons.search),
),
submitOnSuggestionTap: true,
suggestions: lstSuggestions,
textChanged: (queryString){
if(queryString.length >= 3)
queryCompanyNames(queryString);
},
itemBuilder: (context,item){
return Center(
heightFactor: 1,
child: Column(
children: <Widget>[
ListTile(
contentPadding: EdgeInsets.all(2.0),
title: Text(
item,
style: TextRegularStyle.get()),
),
Divider(color: Colors.blueGrey,)
],)
);
},
itemFilter: (item,queryString ){
if(item.toLowerCase().startsWith(queryString.toLowerCase()))
return true;
},
itemSorter: (item1, item2){
return item1.toLowerCase().compareTo(item2.toLowerCase());
},
itemSubmitted: (SelectedItem){
//Not doing here anything as of now.
},
);
//myCompanySearchBox.textField.controller = CompanyNameController,
return myCompanySearchBox;
}
queryCompanyNames(String queryString) async
{
/*Calling the MCAutoSuggestionsGetter which fetches the suggestions from the internet. This step is working fine. We are getting a List<String> in "Suggestions" variable below. But when setState() is called, the previous "lstSuggestions" should be cleared and new "Suggestions" should be added. And these newly added suggestions should be displayed. But I am unable to achieve this.*/
MCAutoSuggestionsGetter.fetchSuggestions(queryString).then((Suggestions){
setState((){
lstSuggestions.clear();
lstSuggestions.addAll(Suggestions);
});
});
}
}
My pubspec.yaml -
name: dev1_stock_meter
description: A new Flutter application.
version: 1.0.0+1
environment:
sdk: ">=2.1.0 <3.0.0"
dependencies:
flutter:
sdk: flutter
firebase_core: ^0.2.5+1
firebase_auth: ^0.7.0
fluttertoast: ^3.0.4
autocomplete_textfield: ^1.6.4
html: ^0.13.3+3
http: ^0.12.0
date_format: ^1.0.6
cupertino_icons: ^0.1.2
dev_dependencies:
flutter_test:
sdk: flutter
flutter:
uses-material-design: true
assets:
- images/logo.jpg
fonts:
- family: GoogleSans
fonts:
- asset: fonts/GoogleSans-Regular.ttf
weight: 300
- asset: fonts/GoogleSans-Bold.ttf
weight: 400
Expected Behaviour:
The expected behaviour is when the user types a string that is more than 3 characters long, the suggestions should be fetched from internet and these suggestions should be attached to the AutoCompletTextField and the suggestions should be displayed.