RxJava zip运算符不会发出事件

Question

拥有以下代码：

final List<C1dbg> tmp_debug = new ArrayList<>();
Observable.zip(Observable.just(1), avgObs, C1dbg::aggr).subscribe(c1 -> tmp_debug.add(c1));

final List<Double> avg_debug = new ArrayList<>();
        avgObs.subscribe(avg -> {avg_debug.add(avg);});

...
public static C1dbg aggr( Object v, Double avg) {

            C1dbg r = new C1dbg();
            r.average = avg;

            return r;
        }

执行后avg_debug是如何填充元素的（即avgObs发出事件）而tmp_debug不是？

由于