docs: public void newTransactionHandler(PersistedTransaction tx, PersistedV2Key key) throws Exception {
          listenForUpdates(tx);
          tx.keyId = key.getId();
          tx.walletId = this.descriptor.getKey();
          tx.account = key.account;
          System.out.println("Incoming transaction captured in API service: " + tx.toString());
          transactionDAO.create(tx);
          WalletChange change = new WalletChange(tx.value, getBalance(), createKey(key.account).address, tx);
          WalletChangeMessage out = new WalletChangeMessage();
          out.setCommand(Command.BALANCE_CHANGE_RECEIVED);
          out.setKey(this.descriptor.key);
          out.setPayload(change);
          router.sendUpdate(this.descriptor.key, out);
      }