[syslog-ng] Customizing syslog-ng snmp() destination option

Hi All, I am using syslog-ng v3.30 and forwarding snmp traps from this server using snmp() destination option - [cid:image001.png@01D839F6.A0D8F220] I wanted to add a field "agent-addr" as part of the trap & not in the variable-binding. This field "agent-addr" will contain the IP address of the device which is sending the syslog message to the syslog server. How can I add a customized filed as part of the trap? Regards, Shivani Maurya