message: Fix container expression items getter function
diff: @@ -311,7 +311,7 @@ cpp2::ErrorCode QueryBaseProcessor<REQ, RESP>::checkExp(const Expression* exp,
  case Expression::Kind::kList: {
  auto* listExp = static_cast<const ListExpression*>(exp);
  for (auto& item : listExp->items()) {
  - auto ret = checkExp(item, returned, filtered, updated);
  + auto ret = checkExp(item.get(), returned, filtered, updated);
  if (ret != cpp2::ErrorCode::SUCCEEDED) {
  return ret;
  }
  @@ -321,7 +321,7 @@ cpp2::ErrorCode QueryBaseProcessor<REQ, RESP>::checkExp(const Expression* exp,
  case Expression::Kind::kSet: {
  auto* setExp = static_cast<const SetExpression*>(exp);
  for (auto& item : setExp->items()) {
  - auto ret = checkExp(item, returned, filtered, updated);
  + auto ret = checkExp(item.get(), returned, filtered, updated);
  if (ret != cpp2::ErrorCode::SUCCEEDED) {
  return ret;
  }
  @@ -331,7 +331,7 @@ cpp2::ErrorCode QueryBaseProcessor<REQ, RESP>::checkExp(const Expression* exp,
  case Expression::Kind::kMap: {
  auto* mapExp = static_cast<const MapExpression*>(exp);
  for (auto& item : mapExp->items()) {
  - auto ret = checkExp(item.second, returned, filtered, updated);
  + auto ret = checkExp(item.second.get(), returned, filtered, updated);
  if (ret != cpp2::ErrorCode::SUCCEEDED) {
  return ret;
  }
  