protected TransactionAddedResult addToNextLayer(
      final NavigableMap<Long, PendingTransaction> senderTxs,
      final PendingTransaction pendingTransaction,
      final int distance,
      final AddReason addReason) {
    final int nextLayerDistance;
    if (senderTxs.isEmpty()) {
      nextLayerDistance = distance;
    } else {
      nextLayerDistance = (int) (pendingTransaction.getNonce() - (senderTxs.lastKey() + 1));
    }
    return nextLayer.add(pendingTransaction, nextLayerDistance, addReason);
  }
Return the full content of this layer, organized as a list of sender pending txs. For each
sender the collection pending txs is ordered by nonce asc.

@return a list of sender pending txs
ethereum/eth/src/main/java/org/hyperledger/besu/ethereum/eth/transactions/layered/AbstractTransactionsLayer.java