Hi There,
Looking at the icon of this policy - it looks like a custom assertion created on site for you guys.
You would need to identify who wrote it and if they can compile it with latest Java version to make sure it is compatible with latest versions of the gateway.
Check your 9.1 Gateway:
/opt/SecureSpan/Gateway/runtime/modules/lib directory for something like 'JsonPatchAssertion.jar'
Once compiled with later GW Java/SDK - you should be able to use it on 9.3 (or 9.2 if you compile it there).
Hope this helps,
Regards,
Amit.