message: change enum to class
diff: @@ -876,7 +876,7 @@ fc::time_point producer_plugin_impl::calculate_pending_block_time() const {
  return block_time;
  }
  -enum unapplied_transaction_category {
  +enum class tx_category {
  PERSISTED,
  UNEXPIRED_UNPERSISTED,
  EXPIRED,
  @@ -995,21 +995,21 @@ producer_plugin_impl::start_block_result producer_plugin_impl::start_block(bool
  auto unapplied_trxs = chain.get_unapplied_transactions();
  apply_trxs.reserve(unapplied_trxs.size());
  - auto calculate_transaction_category = [&](const transaction_metadata_ptr& trx) -> unapplied_transaction_category {
  + auto calculate_transaction_category = [&](const transaction_metadata_ptr& trx) {
  if (trx->packed_trx.expiration() < pbs->header.timestamp.to_time_point()) {
  - return EXPIRED;
  + return tx_category::EXPIRED;
  } else if (persisted_by_id.find(trx->id) != persisted_by_id.end()) {
  - return PERSISTED;
  + return tx_category::PERSISTED;
  } else {
  - return UNEXPIRED_UNPERSISTED;
  + return tx_category::UNEXPIRED_UNPERSISTED;
  }
  };
  for (auto& trx: unapplied_trxs) {
  auto category = calculate_transaction_category(trx);
  - if (category == EXPIRED || (category == UNEXPIRED_UNPERSISTED && _producers.empty())) {
  + if (category == tx_category::EXPIRED || (category == tx_category::UNEXPIRED_UNPERSISTED && _producers.empty())) {
  chain.drop_unapplied_transaction(trx);
  - } else if (category == PERSISTED || (category == UNEXPIRED_UNPERSISTED && _pending_block_mode == pending_block_mode::producing)) {
  + } else if (category == tx_category::PERSISTED || (category == tx_category::UNEXPIRED_UNPERSISTED && _pending_block_mode == pending_block_mode::producing)) {
  apply_trxs.emplace_back(std::move(trx));
  }
  }
  