I upgraded my packages today and suddenly am unable to run ‘flutter build appbundle’ it give the following error:

/Users/User/.pub-cache/hosted/pub.dev/firebase_core-3.0.0/android/src/main/java/io/flutter/plugins/firebase/core/FlutterFirebaseCoreRegistrar.java:19: error: cannot find symbol
        LibraryVersionComponent.create(BuildConfig.LIBRARY_NAME, BuildConfig.LIBRARY_VERSION));
                                       ^
  symbol:   variable BuildConfig
  location: class FlutterFirebaseCoreRegistrar
/Users/User/.pub-cache/hosted/pub.dev/firebase_core-3.0.0/android/src/main/java/io/flutter/plugins/firebase/core/FlutterFirebaseCoreRegistrar.java:19: error: cannot find symbol
        LibraryVersionComponent.create(BuildConfig.LIBRARY_NAME, BuildConfig.LIBRARY_VERSION));
                                                                 ^
  symbol:   variable BuildConfig
  location: class FlutterFirebaseCoreRegistrar
2 errors

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':firebase_core:compileReleaseJavaWithJavac'.
> Compilation failed; see the compiler error output for details.

* Try:
> Run with --info option to get more log output.
> Run with --scan to get full insights.

BUILD FAILED in 5s

I have searched around the web and it says ‘BuildConfig class not being found during the compilation of the firebase_core plugin’. Any ideas what do I have to do for BuildConfig? TIA.