In 7.3.1+ you can create a Data Transform with "Data model format" (under "Additional configuration options") to 'JSON'.
The simplest case; you can just set 'Auto-map all date' - keeping the "top element structure" as "Object".
That's it; the incoming JSON (so long as it 'fits') - will get mapped to the named properties.
(In fact, the properties don't actually have to exist to demonstrate the Data Transform working - but you'll want to create them in real life).
You then call the DT with two PARAMs:
Set 'executionMode' to "DESERIALIZE"; set the jsonData to the full string of the JSON.
[ NOTE: I had to change your JSON - the leading "." (dot) doesn't work - since (I presume) that is ambiguous for the PRPC expression language - where the "." prefix is used when deferencing Properties; basically you are not allowed property names that start with a "." (dot) ]
Did you find any resolution for this. Even I am facing same issue. I do have pzExternalName qualifier in my Pega Property but the JSON data transform not picking up. If you find any resolution pls post it over here.