How can I define UserTask using JSON file?

[codecodecookie]

I need to implement an approval type process, but the process is dynamic and variable, so I need to use JSON files to define user activities, but I have not been able to use usertask in JSONprimitives, any examples of this can be used for reference, would you be grateful。

[codecodecookie]

The follow picture is that my JSON file for implements a recur flow,but my input or stopcondition setting has some error ，lead to that start workflow but recur step not work,who can tell me how to fix it , thanks in advance