@SuppressWarnings("rawtypes")
    public static void setOnFlowableAssembly(@Nullable Function<? super Flowable, ? extends Flowable> onFlowableAssembly) {
        if (lockdown) {
            throw new IllegalStateException("Plugins can't be changed anymore");
        }
        RxJavaPlugins.onFlowableAssembly = onFlowableAssembly;
    }