Repository: flutter
Issue: Flutter fix rule for AppBarTheme brightness is not suggested
Labels: team,framework,f: material design,dependency: dart,d: stackoverflow,has reproducible steps,c: tech-debt,found in release: 2.5,found in release: 2.6,team-design,triaged-design

Hello,

I was upgrading an older project from Flutter 2.2.3 to 2.5.3 and began fixing deprecation issues.
I noticed that the fix for migrating `brightness` for `AppBarTheme` was not being suggested by VSCode.
Either there is no fix rule for this deprecation (unlikely, since a deprecation without a fix rule would not get approved),
or the specific rule is not being recognised by the IDE?

While I have both Android Studio and VSCode installed, the issue happened on VSCode.
I have not tested it on Android Studio.

cc @Piinks

## Steps to Reproduce

1. run flutter create bug
2. update the theme of the app to include an `AppBarTheme` with `brightness: Brightness.light`
3. click on the lightbulb icon to open the suggestions
(I did notice that for other fixes, it only shows up in the `Problems` panel of VSCode)
4. observe that the fix is not present in the suggestions

**Expected results:** 
VSCode suggests a fix rule as an option when clicking the lightbulb.

**Actual results:**
The fix rule is not present in the suggestions, and I have to fix it manually.

```
[✓] Flutter (Channel stable, 2.5.3, on macOS 12.0.1 21A559 darwin-x64, locale en-BE)
    • Flutter version 2.5.3 at /Users/navaronbracke/Documents/flutter_dev/flutter
    • Upstream repository git@github.com:navaronbracke/flutter.git
    • Framework revision 18116933e7 (4 weeks ago), 2021-10-15 10:46:35 -0700
    • Engine revision d3ea636dc5
    • Dart version 2.14.4

[✓] Android toolchain - develop for Android devices (Android SDK version 30.0.3)
    • Android SDK at /Users/navaronbracke/Library/Android/sdk
    • Platform android-31, build-tools 30.0.3
    • ANDROID_HOME = /Users/navaronbracke/Library/Android/sdk
    • Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6915495)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Xcode 13.1, Build version 13A1030d
    • CocoaPods version 1.10.1

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 4.1)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6915495)

[✓] VS Code (version 1.62.2)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.28.0

[✓] Connected device (1 available)
    • Chrome (web) • chrome • web-javascript • Google Chrome 95.0.4638.69

• No issues found!
```

https://user-images.githubusercontent.com/23480364/141649933-0e122300-6a37-455d-ac29-17f6daed89f3.mov