trait T {
    fun foo(a: Int = 1, b: String = "2")
}

open class A: T {
    override fun foo(a: Int, b: String) {
        throw UnsupportedOperationException()
    }
}

class B: A() {
    override fun foo(a: Int, b: String) {
        throw UnsupportedOperationException()
    }
}