jsonFormat query parameter send in http request

I have a virtualised service which will be used by external applications to send the json data in gzip compressed format. Header will be set to Content-Type=application/json and Content-Encoding=gzip.

To test this API I created a flow service which will use a custom java service to gzip the json content and send it as bytes with the API query parameter set to jsonFormat=bytes. This is expected to override the default json parser setting (watt.server.http.jsonFormat=parsed) at the IS. Which works as expected if i call the IS service URL directly, but when I call the virtualised service, this query parameter is not reaching IS. Looking at the mediator logs, the API parameter is successfully send in, but not appended to the IS Service URL which is called from the mediator. In this case Im getting a json parse exception in the IS and restoring the pipeline, jsonBytes or jsonFormat variables are not been found.

Any possible reason for this parameter getting ignored or any other work around to send the gzip json data please?