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Shouldn’t this be allowed since we are implementing `FooWrapper` (which is allowed) and `FooWrapper` already extends `Foo`?
```sealed interface Foo

interface FooWrapper: Foo {
    val wrappedFoo: Foo
}

// other module

class FooWrapperImpl(
    override val wrappedFoo: Foo,
): FooWrapper, Foo by wrappedFoo // Inheritance of sealed classes or interfaces from different module is prohibited```

You can mark `FooWrapper` as sealed, and neither would be allowed. But as it stands, FooWrapper is not sealed.

I think the way I see it is that the `Foo by wrappedFoo` is just there as a convenience to implement part of the `FooWrapper` interface. It’s not changing what `FooWrapperImpl` does or does not implement.

Seems reasonable to be allowed, please file an issue.

<https://youtrack.jetbrains.com/issue/KT-57275/Allow-extension-of-sealed-interface-when-also-extending-non-sealed-sub-interface>