Upgrade null safety example (#748)

null_safety/README.md

@@ -1,7 +1,7 @@
 # Null safety Flutter example
 
-This folder contains a demonstration of the upcoming Dart feature, sound null
-safety. For additional information about this feature, see
+This folder contains a demonstration of Dart's sound null
+safety feature. For additional information about this feature, see
 https://dart.dev/null-safety.
 
 The folder contains two sample Flutter apps:
@@ -27,8 +27,4 @@ The folder contains two sample Flutter apps:
 
 ## Running the example code
 
-This sample is
-[experimental](https://github.com/flutter/samples/tree/master/experimental), and
-requires using a **beta channel** Flutter SDK. You can change to the beta
-channel with `flutter channel beta` followed by `flutter upgrade` (don't forget
-to change back to `flutter channel stable` for production use.
+This sample requires Flutter 2.0 or later.

null_safety/null_safe_app/pubspec.lock

@@ -7,42 +7,42 @@ packages:
       name: async
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.5.0-nullsafety.3"
+    version: "2.5.0"
   boolean_selector:
     dependency: transitive
     description:
       name: boolean_selector
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.1.0-nullsafety.3"
+    version: "2.1.0"
   characters:
     dependency: transitive
     description:
       name: characters
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.0-nullsafety.5"
+    version: "1.1.0"
   charcode:
     dependency: transitive
     description:
       name: charcode
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.2.0-nullsafety.3"
+    version: "1.2.0"
   clock:
     dependency: transitive
     description:
       name: clock
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.0-nullsafety.3"
+    version: "1.1.0"
   collection:
     dependency: transitive
     description:
       name: collection
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.15.0-nullsafety.5"
+    version: "1.15.0"
   cupertino_icons:
     dependency: "direct main"
     description:
@@ -56,7 +56,7 @@ packages:
       name: fake_async
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.2.0-nullsafety.3"
+    version: "1.2.0"
   flutter:
     dependency: "direct main"
     description: flutter
@@ -73,21 +73,21 @@ packages:
       name: matcher
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.12.10-nullsafety.3"
+    version: "0.12.10"
   meta:
     dependency: transitive
     description:
       name: meta
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.3.0-nullsafety.6"
+    version: "1.3.0"
   path:
     dependency: transitive
     description:
       name: path
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.8.0-nullsafety.3"
+    version: "1.8.0"
   sky_engine:
     dependency: transitive
     description: flutter
@@ -99,56 +99,56 @@ packages:
       name: source_span
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.8.0-nullsafety.4"
+    version: "1.8.0"
   stack_trace:
     dependency: transitive
     description:
       name: stack_trace
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.10.0-nullsafety.6"
+    version: "1.10.0"
   stream_channel:
     dependency: transitive
     description:
       name: stream_channel
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.1.0-nullsafety.3"
+    version: "2.1.0"
   string_scanner:
     dependency: transitive
     description:
       name: string_scanner
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.0-nullsafety.3"
+    version: "1.1.0"
   term_glyph:
     dependency: transitive
     description:
       name: term_glyph
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.2.0-nullsafety.3"
+    version: "1.2.0"
   test_api:
     dependency: transitive
     description:
       name: test_api
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.2.19-nullsafety.6"
+    version: "0.2.19"
   typed_data:
     dependency: transitive
     description:
       name: typed_data
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.3.0-nullsafety.5"
+    version: "1.3.0"
   vector_math:
     dependency: transitive
     description:
       name: vector_math
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.1.0-nullsafety.5"
+    version: "2.1.0"
 sdks:
-  dart: ">=2.12.0-29 <3.0.0"
-  flutter: ">=1.24.0-3.0"
+  dart: ">=2.12.0 <3.0.0"
+  flutter: ">=2.0.0"

null_safety/null_safe_app/pubspec.yaml

@@ -1,16 +1,16 @@
 name: null_safe_app
 description: A new Flutter project.
 publish_to: 'none' # Do not publish apps & package using the null safety experiment.
-version: 1.1.0
+version: 1.2.0
 
 environment:
-  sdk: ">=2.12.0-29 <3.0.0"
-  flutter: ">=1.24.0-3.0"
+  sdk: ">=2.12.0 <3.0.0"
+  flutter: ">=2.0.0"
 
 dependencies:
   flutter:
     sdk: flutter
-  cupertino_icons: ^1.0.0
+  cupertino_icons: ^1.0.2
 
 dev_dependencies:
   flutter_test: