@Override
      public @NotNull List<Key> currentStack() {
        List<Key> result = new ArrayList<>();
        for (MyKey pair : ourStack.get().progressMap.keySet()) {
          if (pair.guardId.equals(id)) {
            //noinspection unchecked
            result.add((Key)pair.userObject);
          }
        }
        return Collections.unmodifiableList(result);
      }
@Override
      public @NotNull List<Key> currentStack()