@CheckReturnValue
    @SchedulerSupport(SchedulerSupport.NONE)
    public final Observable<T> onErrorReturn(Function<? super Throwable, ? extends T> valueSupplier) {
        ObjectHelper.requireNonNull(valueSupplier, "valueSupplier is null");
        return RxJavaPlugins.onAssembly(new ObservableOnErrorReturn<T>(this, valueSupplier));
    }