SmppTransactionHandle is not unique enough on reset of SMPP connections

[vetss]

I have copied an issue from SMSC GW RestComm/smscgateway#142
that corresponds to smpp-extensions now.

At present SmppTransactionHandle is created using ESME name and sequence number from SubmitSM/DeliverSM. This mechanism is not unique enough and causes issues in case an SMPP client connects/disconnects at short intervals due to network issues or by design. The sequence numbers are restarted from 0 on smpp clients mostly and thus SMSC errors out stating Activity/Handle already exists.

We need a way to may be use socketId or connectiontime as an added key to uniquely create SMPP transactions in the system.

https://github.com/RestComm/jain-slee.smpp/blob/master/resources/smpp/ra/src/main/java/org/restcomm/slee/resource/smpp/SmppTransactionHandle.java#L38