Here is how it was resolved:
The request payload is like the sample below:
POST /value/value.action HTTP/1.1
Content-Type: application/x-www-form-urlencoded
shopInputDoJson={JSON payload}
The Recorder, with the REST and JSON DPH, wasn't recognizing the JSON payload.
To parse the JSON payload and recognize the arguments we used the following DPHs
REST Data Protocol
Delimited Text Data Protocol
Request Data Manager
JSON 2.0
Request Data Manager
No changes with the URL rules provided by the REST DPH.
For the Delimited Text Request, selected the RegEx Matching Fields and provided \{.* - this would delimiter the JSON payload and create an argument (val1) with the request payload.
For the first Request Data Manager, added an action to the Action List:
Action = Move; Source Type = argument; Source Name = val1; Target Type = request body.
After the JSON DPH is applied and JSON payload is parsed, we could use the second Request Data Manager and add two actions to the Action List:
Action = Delete; Source Type = request body
Action = Delete; Source Type = argument; Source Name = shopInputDoJson