Web API that connects to process model -I need to pass input parameter different and get a different output parameter can anyone help me out?

Hi Appian team,

Web API that connects to process model -I need to pass input parameter different and get a different output parameter can anyone help me out with this , now whatever am passing as input parameter to processparameter same am getting as output parameter as process info.Please edit below code accordingly

below is the currently used web API code snippet:

a!startProcess(
processModel: cons!xxxxxxxxx
processParameters: {
xxxxxxxxxx : a!fromJson(
http!request.body
)
},
onSuccess: a!httpResponse(
statusCode: 200 ,
headers: {
a!httpHeader(name: "Content-Type", value: "application/json")
},
body: a!toJson(
fv!processInfo
)
),
onError: a!httpResponse(
statusCode: 500,
headers: {
a!httpHeader(name: "Content-Type", value: "application/json")
},
body: a!toJson(
{
error: "There was an error starting the process"
}
)
)
)