In the form modeler allow to reference variables in HTML editor

We have a step in our process where we need that our users to visualize a PDF file in the form related to a user task. That PDF is dynamically generated by a previously work item handler in the process, so the link changes at each process execution.

We need to allow the user to visualize this file that has a dynamic link in the form. In a higher level, maybe a variable defined in the process could be referenced just like ${variableName} or something like that in the HTML code...