ProxyFactory doesn't work when used from Kotlin

[sndre]

I'm wondering whether ProxyFactory is expected to work when used from Kotlin. I'm trying unsuccessfully to make this real simple test pass:

class ProxyFactoryKotlinTest {
    open class LongLoader {
        fun load(): Long {
            return 1
        }
    }

    fun <T> proxy(klass: Class<T>): T {
        val proxyFactory = ProxyFactory()
        proxyFactory.superclass = klass
        val handler =
            MethodHandler { _: Any?, _: Method, _: Method?, _: Array<Any?> ->
                2L
            }
        return klass.cast(
            proxyFactory.create(
                arrayOf(),
                arrayOf(),
                handler
            )
        )
    }

    @Test
    fun test() {
        assertEquals(2, proxy(LongLoader::class.java).load())
    }
}

Is it test setup or is it an issue with using ProxyFactory from Kotlin?