Update to null safety

example/lib/main.dart

@@ -1,5 +1,5 @@
 import 'package:calendarro/date_utils.dart';
-import 'package:flutter/material.dart';
+import 'package:flutter/material.dart' hide DateUtils;
 import 'package:calendarro/calendarro.dart';
 
 void main() => runApp(new MyApp());
@@ -19,15 +19,14 @@ class MyApp extends StatelessWidget {
 
 class MyHomePage extends StatelessWidget {
   final String title;
-  Calendarro monthCalendarro;
 
-  MyHomePage({Key key, this.title}) : super(key: key);
+  MyHomePage({Key? key, required this.title}) : super(key: key);
 
   @override
   Widget build(BuildContext context) {
     var startDate = DateUtils.getFirstDayOfCurrentMonth();
     var endDate = DateUtils.getLastDayOfNextMonth();
-    monthCalendarro = Calendarro(
+    final monthCalendarro = Calendarro(
         startDate: startDate,
         endDate: endDate,
         displayMode: DisplayMode.MONTHS,

example/pubspec.lock

@@ -7,42 +7,63 @@ packages:
       name: async
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.2.0"
+    version: "2.6.1"
   boolean_selector:
     dependency: transitive
     description:
       name: boolean_selector
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.0.4"
+    version: "2.1.0"
   calendarro:
     dependency: "direct dev"
     description:
       path: ".."
       relative: true
     source: path
-    version: "1.0.1"
+    version: "1.2.0"
+  characters:
+    dependency: transitive
+    description:
+      name: characters
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.1.0"
   charcode:
     dependency: transitive
     description:
       name: charcode
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.2"
+    version: "1.2.0"
+  clock:
+    dependency: transitive
+    description:
+      name: clock
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.1.0"
   collection:
     dependency: transitive
     description:
       name: collection
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.14.11"
+    version: "1.15.0"
   cupertino_icons:
     dependency: "direct main"
     description:
       name: cupertino_icons
       url: "https://pub.dartlang.org"
     source: hosted
     version: "0.1.2"
+  fake_async:
+    dependency: transitive
+    description:
+      name: fake_async
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.2.0"
   flutter:
     dependency: "direct main"
     description: flutter
@@ -59,35 +80,21 @@ packages:
       name: matcher
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.12.5"
+    version: "0.12.10"
   meta:
     dependency: transitive
     description:
       name: meta
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.6"
+    version: "1.3.0"
   path:
     dependency: transitive
     description:
       name: path
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.6.2"
-  pedantic:
-    dependency: transitive
-    description:
-      name: pedantic
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "1.7.0"
-  quiver:
-    dependency: transitive
-    description:
-      name: quiver
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "2.0.3"
+    version: "1.8.0"
   sky_engine:
     dependency: transitive
     description: flutter
@@ -99,55 +106,55 @@ packages:
       name: source_span
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.5.5"
+    version: "1.8.1"
   stack_trace:
     dependency: transitive
     description:
       name: stack_trace
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.9.3"
+    version: "1.10.0"
   stream_channel:
     dependency: transitive
     description:
       name: stream_channel
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.0.0"
+    version: "2.1.0"
   string_scanner:
     dependency: transitive
     description:
       name: string_scanner
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.0.4"
+    version: "1.1.0"
   term_glyph:
     dependency: transitive
     description:
       name: term_glyph
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.0"
+    version: "1.2.0"
   test_api:
     dependency: transitive
     description:
       name: test_api
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.2.5"
+    version: "0.3.0"
   typed_data:
     dependency: transitive
     description:
       name: typed_data
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.6"
+    version: "1.3.0"
   vector_math:
     dependency: transitive
     description:
       name: vector_math
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.0.8"
+    version: "2.1.0"
 sdks:
-  dart: ">=2.2.2 <3.0.0"
+  dart: ">=2.12.0 <3.0.0"

example/pubspec.yaml

@@ -1,6 +1,9 @@
 name: sample
 description: sample app
 
+environment:
+  sdk: ">=2.12.0 <3.0.0"
+
 dependencies:
   flutter:
     sdk: flutter