Kotlin: double semicolon (reflection) operator over

So I was working with VertX Web, trying to make it work with Kotlin. There's a router and you have to say something like

val vertx = Vertx.vertx()
val server = vertx.createHttpServer()
val router = Router.router(vertx)
server.requestHandler(router::accept)

But it doesn't work. What am I doing wrong? When I use it on Kotlin defined classes, it behaves normally. Is it done on purpose?

Whatever, I had to do it manually like this

server.requestHandler{router.accept(it)}