@NonNull
    public static List<TimerTask> unwraps(@Nullable Collection<? extends TimerTask> tasks) {
        if (tasks == null) return Collections.emptyList();

        List<TimerTask> copy = new ArrayList<>();
        for (TimerTask task : tasks) {
            if (!(task instanceof TtlTimerTask)) copy.add(task);
            else copy.add(((TtlTimerTask) task).getTimerTask());
        }
        return copy;
    }
Unwrap {@link TtlTimerTask} to the original/underneath one.
<p>
Invoke {@link #unwrap(TimerTask)} for each element in input collection.
<p>
This method is {@code null}-safe, when input {@code TimerTask} parameter is {@code null}, return a empty list.

@see #unwrap(TimerTask)
@since 2.10.2
ttl2-compatible/src/main/java/com/alibaba/ttl/TtlTimerTask.java