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