fun Throwable.lastCause(): Throwable {
    val dejaVu = Collections.newSetFromMap(IdentityHashMap<Throwable, Boolean>())
    dejaVu.add(this)
    var curThrowable = this
    while (curThrowable.cause != null && !dejaVu.contains(curThrowable.cause)) {
        curThrowable = curThrowable.cause!!
        dejaVu.add(curThrowable)
    }
    return curThrowable
}