private TransactionAddedResult addToNextLayer(
      final PendingTransaction pendingTransaction, final int distance, final AddReason addReason) {
    return addToNextLayer(
        txsBySender.getOrDefault(pendingTransaction.getSender(), EMPTY_SENDER_TXS),
        pendingTransaction,
        distance,
        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