How to use tokens in the Completed URL? I need to send data in the URL to the receiving server so that two fields from a survey form is put in the Completed URL string. It looks like it should be possible to use tokens for this, but I can't seem to figure out the correct syntax to use.  

I need to send the response to a URL on the form   

https://server.tld/sub/value1/value2  

where value1 and value2 are fetched from form fields and the rest is static.  

According to https://www.drupal.org/project/webform/issues/3021818 this should be possible, if I only could find the correct syntax to use to add the tokens.  

Background
The user gets a link to the survey form in a text message. After filling in the form, the Remote Post handler functionality in Webform should post the results to an external server that expects the survey ID and user alias as parts of the URL (for reasons unknown to me, but apparently expensive and difficult to change) for the purposes of knowing when the user has filled in the survey so as to avoid sending out a reminder.  

What I have tried
I have tried formatting the Completed URL string in various ways; like for example  

http://example.com/%value[my_fieldset][a_value_in_the_form]  

and

http://example.com/%value  

but I just get a URL invalid error response when I try to save the setting.
I managed to get it going using the standard tokens so in Completed URL I had https://URL/API?query=[webform_submission:values:fieldname] - so just swap out fieldname for the key in the webform you want to pass