unsafe_variance lint on `builder`

main.dart

import 'package:flutter/widgets.dart';

class SomeBuilder<T> extends StatefulWidget {
  const SomeBuilder({
    required this.initialValue,
    required this.builder,
    this.child,
    super.key, // ignore: unused_element
  });

  final T initialValue;
  final ValueWidgetBuilder<T> builder; // LINT - This type is unsafe: a type parameter occurs in a non-covariant position

  final Widget? child;

  @override
  State<SomeBuilder<T>> createState() => _SomeBuilderState<T>();
}

/// State for widget SomeBuilder.
class _SomeBuilderState<T> extends State<SomeBuilder<T>> {
  late final ValueNotifier<T> _notifier = ValueNotifier(widget.initialValue);

  @override
  Widget build(BuildContext context) => ValueListenableBuilder(
        valueListenable: _notifier,
        builder: (context, value, child) => widget.builder(context, value, child),
        child: widget.child,
      );
}