Unbound generic copyWith (or even nullable bound) does not respect type nullability

[dzsonni]

Nullability causes class to generate non-nullable copyWith function, basically preventing the copy from ever setting it to null.

classs Foo<T extends Object?> with FooMappable<T>{
    const Foo(this.value);
    
    final T value;
}

final Foo<String?> foo = Foo('foo');

foo.copyWith(null);

The value of foo after the copyWith will still be 'foo'.