code: private void persistTransactions(Transaction tx, String blockNumber)
      {
  
          LOGGER.debug("Going to save transactions for Block - " + getBlockNumberWithRawData(blockNumber) + "!");
          try
          {
              em.persist(tx);
              LOGGER.debug("Transaction with hash " + tx.getHash() + " is stored!");
          }
          catch (Exception ex)
          {
              LOGGER.error("Transaction with hash " + tx.getHash() + " is not stored. ", ex);
              throw new KunderaException("transaction with hash " + tx.getHash() + " is not stored. ", ex);
          }
  
      }
docs: Persist transactions.
  
  @param tx
  the transaction
  @param blockNumber
  the block number