Body of invokeurl, from Zoho Flow, is being received as NULL

Body of invokeurl, from Zoho Flow, is being received as NULL

I have the following simplified Zoho Flow function:

  2. headers = Map();
  3. headers.put("Content-Type","application/json");
  4. res = invokeurl
  5. [
  6. url :"https://sandbox.zohoapis.com/crm/v2/functions/flow_to_queue_portal_task/actions/execute?<api_key_stuff>"
  7. type :POST
  8. parameters:{"FOO":"BAZ"}
  9. headers:headers
  10. ];
The function on the receiving end of this invokeurl, `flow_to_queue_portal_task(String paramsMap)` says the following:
  1. return "FOO " + paramsMap;
The output returned in the first function's `info` is:
  1. {
   code : "success",
   details : {
      output : "FOO null",
      output_type : "string",
      id : "712085000000252005"
   },
   message : "function executed successfully"
}
Why is my parameters body being received as `null`?