docs: @Nonnull
      public static <T> List<TtlCallable<T>> gets(@Nullable Collection<? extends Callable<T>> tasks, boolean releaseTtlValueReferenceAfterCall, boolean idempotent) {
          if (null == tasks) return Collections.emptyList();
  
          List<TtlCallable<T>> copy = new ArrayList<TtlCallable<T>>();
          for (Callable<T> task : tasks) {
              copy.add(TtlCallable.get(task, releaseTtlValueReferenceAfterCall, idempotent));
          }
          return copy;
      }