Webhooks template variables not working in responseTopic

It looks like the responseTopic field in a webhook does not respond to template variables. Here is a simplified example:

"event": "test-hook",
"responseTopic": "{{myVar}}_loginToken",
"noDefaults": true,
"mydevices": true,
"requestType": "POST",
"url": "http://www.xxxxx.net/users/login",

Here is the code:

#include "application.h"
void setup(){
  String dataString = "{\"myVar\":\"test\"}";
void loop(){

The text, “test” is properly appended to the json portion of the post via {{myVar}}, but the responseTopic always appends a null for {{myVar}}.

  • Is this expected behavior or a bug?
  • Should I expect to be able to use a template variable in the
    responseTopic field?