Any other way of marking internal APIs in interfaces?

interface IFoo {
    @Suppress("DEPRECATION")
    @RequiresOptIn(
        level = RequiresOptIn.Level.ERROR,
        message = "This API is DANGEROUS, internal and should not be used. It could be removed or changed without notice."
    )
    @Experimental(level = Experimental.Level.ERROR)
    @Target(
        AnnotationTarget.PROPERTY
    )
    annotation class DangerousInternalAPI

    @DangerousInternalAPI
    val internalState: MutableMap<KType, Any>

That’s basically what the

internal

access modifier is for

Yes, but you can't make a method/field internal in an interface

what about defining a separate internal interface?

Thought about that, but I need to make inline methods on the public interface to use refined and they need access to the internal interface, so I end right back where I started 😢

maybe this shouldn’t be an interface at all, considering the amount of implementation it’s offering