¿Cómo se usa Flowable.generate de Kotlin?

Aquí hay un bash fallido de stub en Flowable.generate (con más annotations de tipo de las que normalmente usaría):

val xs: Flowable<String> = Flowable.generate<Int, String>( java.util.concurrent.Callable<Int> { -> 0 }, io.reactivex.functions.BiConsumer<Int, String> { t1, t2 -> } ) 

La firma de Java que me gustaría usar es:

 public static <T, S> Flowable<T> generate(Callable<S> initialState, final BiConsumer<S, Emitter<T>> generator) 

El error que estoy obteniendo es:

 Error:(145, 12) None of the following functions can be called with the arguments supplied: @CheckReturnValue @BackpressureSupport @SchedulerSupport public final fun <T : Any!, S : Any!> generate(p0: (() -> (???..???))!, p1: (((???..???), Emitter<(???..???)>!) -> Unit)!): Flowable<(???..???)>! defined in io.reactivex.Flowable @CheckReturnValue @BackpressureSupport @SchedulerSupport public final fun <T : Any!, S : Any!> generate(p0: (() -> (???..???))!, p1: ((???, Emitter<(???..???)>) -> ???)!): Flowable<(???..???)>! defined in io.reactivex.Flowable @CheckReturnValue @BackpressureSupport @SchedulerSupport public open fun <T : Any!, S : Any!> generate(p0: Callable<(???..???)>!, p1: BiConsumer<(???..???), Emitter<String!>!>!): Flowable<String!>! defined in io.reactivex.Flowable @CheckReturnValue @BackpressureSupport @SchedulerSupport public open fun <T : Any!, S : Any!> generate(p0: Callable<Int!>!, p1: BiFunction<Int!, Emitter<(???..???)>!, Int!>!): Flowable<(???..???)>! defined in io.reactivex.Flowable 

¿Qué debería estar alimentando el comstackdor?

El tipo para generate() debe ser <String, Int> y el tipo para BiConsumer debe ser <Int, Emitter<String>> .

 val xs: Flowable<String> = Flowable.generate<String, Int>( java.util.concurrent.Callable<Int> { -> 0 }, io.reactivex.functions.BiConsumer<Int, Emitter<String>> { t1, t2 -> } )