Attempt to Populate System Parameters with API Response from Dialogflow Webhook Not Working?

[DontWannaBeABot]

Hi, 

I've been able to make a webhook that calls my own nodejs api where i maintain a database of faux employees. The API responds, and I have been able to populate the Agent's response in the fulfillmentResponse Object. I've tried formatting the sessionInfo Object in a number of ways and can't update system parameters like @sys.last-name (Note: I also tried "@sys.last-name" as the parameters key, but it didn't work)? Is there something wrong w/ my JSON formatting? Here's my JSON formatting, and the console.log of what the app sent:

  // Return a successful response
      let jsonResponse = {
        "fulfillmentResponse":{
          "messages": [
            {
              "text": [message]
            }
          ],
        },
        "sessionInfo" :{
          "parameters": {
            "last-name" : result[0].lastName,
            "location" : "Miami",
          }
        }
      }
  res.status(200).send(jsonResponse); 
  console.log(JSON.stringify(jsonResponse));

----------------------------------console.log output----------------
{"fulfillmentResponse":
   {"messages":[
      {"text":[
         "This is a copy of the employee record I was able to find in my database: \n 
         \nName: Charlie Brown\nPhone: 7045555551\nLocation: Anderson\nEmployee ID: 
         7\nEmail: cbrown@elux.com\nAddress: 1770 James Street Charlotte NC 
         28277\n\nSupervisor: Snoopy"
         ]
      }
     ]
    },
   "sessionInfo":{
      "parameters":{
          "last-name":"Brown","location":"Miami"
         }
      }
    }

[ricconoel]

Just to confirm, you are using Dialogflow CX? Can you provide a sample code on your webhook that can be used to reproduce the issue? Can you try separating the `sessionInfo` object with the `fulfillmentResponse` object just to check if it has the same behavior?