docs: @Nonnull
      public static List<TimerTask> unwraps(@Nullable Collection<? extends TimerTask> tasks) {
          if (null == tasks) return Collections.emptyList();
  
          List<TimerTask> copy = new ArrayList<TimerTask>();
          for (TimerTask task : tasks) {
              if (!(task instanceof TtlTimerTask)) copy.add(task);
              else copy.add(((TtlTimerTask) task).getTimerTask());
          }
          return copy;
      }